Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Ngay day:/ 09 / 2009CAC PHEP TNH CUA CAN BAC HAI I. Mc tiu : - Cng c li cho hc sinh quy tc khai phng nmt tch v nhn cc cn thc bc hai- Nm chc c cc quy tcv vn dng thnh tho vo cc bi tp khai phng mt s , mt biu thc , cch nhn cc cn bc hai vi nhau .- Rn k nng gii mt s bi tp v khai phng mt tch v nhn cc biu thc c cha cn bc hai cng nh bi ton rt gn biu thc c lin quan .II. Chun b ca GV - HS : - GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: Hc thuc cc nh l , quy tc , Gii cc bi tp trong SBT ton 9 tp 1 . III .Bai tap : A/ Trac nghiem :Cau 1: Chon cau ung A/ 4 2 B/V -3a 0vi moi a 3a vo nghaC/) ) ( ( ) ( ) (9 . 16 9. 16 3 . 4 = 12D /16: 25 16 : 25 4: 5 0.8 Cau 2 : Ket qua cua phep tnh 216ala : a/4ab/8a c/ -4a d/4 aCau 3 : Hay ch ra cach tnh sai : a /4.16 4. 16 2.4 8 b/4 4 225 5 25 c/16 9 16 9 4 3 7 + + + d/ 2a a via 0 Cau 4 : Can bac hai so hoc cua 81 la : a/ 9b/-9c/ 81 d/9 BBai tap :1/ Tnh :a/( ) 2 6 6 2 : 12 +b / 2 48 3 24 75 + c/120 2 28 2 452 + d/ () 5 2 3 6 .4 2 8 27 +e/ ()26 3 5 32 +f/ () 3 5 2 3 . 5 60 +g/ ( )214 3 2 6 28 + h/()() 2 5 3 2 2 5 3 2 +2/ Viet cac bieu thc sau ve dang bnh phng:Giao vien : Le Van Hoa Trng THCS Xuan Lam1Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010a /4 2 3 b/7+ 2 10c / 8 + 2 15d/ 6 + 4 23/ Phan tch ra tha so :a/3 3 +b/ 14 7 c/ 10 2 10 + d/ 22 2 2 x x +4/ Rut gon cac bieu thc :/ 4 2 3 3 a b/ 11 6 2 3 2 + +5/Tnh :a/ A = 2 3. 2 3 + b/ B= )()(222 5 2 5 + +c/C = 9 2 14 3 28 + 6/ Tnh : a/75 48 300 + b/98 72 0, 5 8 +c/9 16 49 a a a + vi0 a d/16 2 40 3 90 b b b + ( ) 0 b 7/ Rut gon bieu thc : a/() 2 3 5 5 60 + b/ () 5 2 2 5 5 250 + c/() 28 12 7 7 2 21 +d/ () 3 2 50 2 18 98 +8/Tm x biet : a/25 35 x b/3 12 x c/3 2 9 16 5 x x x + d/ 28 16 2 x x x +

9/ Chng minh : a/22 12 2 6 4 2 4 2 + + b/ 12 3 7 12 3 7 6 + IV. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai.- Tuan sau: Rut gon bieu thc cha can thc bac hai.Giao vien : Le Van Hoa Trng THCS Xuan Lam2Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Ngay day:/ 09 / 2009RUT GON BIEU THC CHA CAN THC BAC HAI A. Mc tiu :- Tip tc cng c li cho hc sinh quy tc a tha s ra ngoi, vo trong du cn;kh mu , trc cn thc mu ca cc biu thc.- Nm chc c cc quy tcv vn dng thnh tho vo cc bi tp - Rn k nng gii mt s bi tp v kh mu, trc cn thc cc biu thc c cha cn bc hai.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: Hc thuc cc nh l , quy tc , Gii cc bi tp trong SBT ton 9 tp 1 . C. Noi dung bai tap.A/ Trac nghiem: Cau 1:a/ ieu kien xac nh cua 3 2 x la b/ ieu kien xac nh cua 22ab la Cau 2:Ghi , S vao cac cau sau:

2 22) [ 2( 3 2)] 2( 3 2) ) ( 3) 31 1) ( 3) ) 2. 8 16 49 3A BC D Cau 3:Chon ket qua ung: 2 2 2 2 22 2 2 2) .(73 72 ) . 145 ) 5. 73 72 5. 29) 199. 99 100 199 ) 3. 14 13 9A c c BC D Cau 4: ien vao cho e c cau ung 3 3 33 31 1 1) ( 0, 3) ................ ) 0, 4.0, 02 ......... .. ) 125 27 ............2 5 3a b c B/ T luan:Bai1: Rut gon cac bieu thc sau: 2 21) ( 0, 3) a A aa ( vi a0) 210 25) 55x xc Cx + (vi x3) Bai 2: Tnh:Giao vien : Le Van Hoa Trng THCS Xuan Lam3Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010

4 22 2) 2 ( 5) ) 14, 4.250 ) 2, 7. 5. 1, 5) (3 5) (3 5) ) 5 3. 5 3a b cd e + + ) 3 2 2 3 2 2 ) 3 5 . 3 5 f g + + +Bai 3 :Thc hien cac phep tnh

5 1 1 4) 49 3 5 80 )2 0, 5 37 4 2 31 1) 2( 75 32 5 3) )3 2 3 2a bc d + ++ + + Bai 4: Rut gon cac bieu thc sau:

6 15 3 1 2) ) :2 5 3 1 2a ab aA Ba a ab+ + + + Bai 5: Giai phng trnh

2) 2. 18 5 2 3 8 ) 3 (2 5 ) 1) 8 2 3 4 0 ) 2 2 9 18 9 2 4 8a x b xc x d x x x+ Bai 6: Cho bieu thc

2 4 42 2x x x xAx x+ + +

a/ Tm ieu kien cua x e bieu thc A co nghab/ Rut gon bieu thc Ac/ Tnh gia tr cua x khi 4 2 2 A D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap hnh hoc: He thc gia canh va goc trong tam giac vuong.Giao vien : Le Van Hoa Trng THCS Xuan Lam4Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Ngay day:/ 10 / 2009H THC GIA CNH V GC TRONG TAM GIC VUNGA. Mc tiu :- Cng c cc h thc v cnh v ng cao trong tam gic vung, h thc v cnh v gc trong tam gic.- Bit s dng cc h thc gii cc dng bi tp lin quan.- Rn tnh cn thn trong tnh ton.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: Hc thuc cc nh l , quy tc .C. Bi tp:I/ Trac nghiem: Bi 1: Gii ABC vung ti A, bit AC = 10 cm , C = 030 . Cu no sau y ngA/AB = 10 3 cm;BC = 20 3 cm;060 B = .B/AB = 10 33cm;BC = 20 33cm;060 B = .C/AB = 5 33cm;BC = 10 33cm;060 B = .D/Kt qu khc.Bi 2: Gii ABC vung ti A, bit BC = 15 cm , 035 B =(lm trn n ch s thp phn th hai). Cu no sau y ngA/AB 12,29 cm;AC 8,61 cm;055 C = . B/AB= 12 cm;AC = 8 cm;055 C = .C/AB= 11,29 cm;AC = 8,80 cm;055 C = .D/C 3 cu u sai.Bi 3: Gii ABC vung ti A, bit AB =5 3cm, AC = 9 cm (lm trn n ch s thp phn th hai, gc lm trn n ). Cu no sau y ngA/BC = 12,49 cm;050 B = .B/AB = 8,65 cm;BC = 12,49 cm;051 B = .C/BC = 12,49 cm;046 B =;044 C = .D/BC = 12,49 cm;050 B =;040 C = .II. Bi tp t lun 1- Gii ABC vung ti C, bit 030 & 2 3 A AB cm = = . 2- Gii ABC vung ti B, bit 060 & 3 5 . A BC cm = =Giao vien : Le Van Hoa Trng THCS Xuan Lam5Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010 3- Gii ABC vung ti A, bit AB = 5 cm & AC = 6 cm. 4- Gii ABC vung ti A, bit BC = 13 cm & AC = 12 cm. 5- Gii ABC vung ti A, bit BC = 12 cm & cos C = 0,7. 6- Cho ABC vung ti B, k ng cao BH & tip tuyn BM (H & M thuc cnh AC). Tnh s o HBM, bit AB = 6 cm & BC = 8 cm. 7- Cho ABC c BH l ng cao, bit HB = 8 cm, HA = 7 cm, HC = 9 cm. Tnh s o cc gc ca tam gic (lm trn n )8- Gii bi tp 62 ( SBT - 98 )GT : ABC ( = 900 ) AH BC ;HB = 25 cm ; HC = 64 cm KL : Tnh gc B , C Gii : Xt ABC ( = 900 ) . Theo h thc lng ta c : AH2 = HB . HC = 25 . 64 = ( 5.8)2 AH = 40 ( cm ) Xt vung HAC c : tg C = AH 400, 625HC 64 C 320 Do 0 0 0 0B C 90B 90 32 58 + .9. Cho ABC vuong tai A ( AB AC ) , ng cao AH . Biet AB = 15 cm , BH = 9 cm .a/ Tnh AH , AC , BC , AH .b/ Tnh chu vi va dien tch ABC .c/ Tnh so o goc B,C ( tron en phut ) .D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap hnh hoc: He thc gia canh va goc trong tam giac vuong.********************************Giao vien : Le Van Hoa Trng THCS Xuan Lam6HBCAGiao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Ngay day:/ 10 / 2009H THC GIA CNH V GC TRONG TAM GIC VUNGA. Mc tiu :- Tip tc cng c cc h thc v cnh v ng cao trong tam gic vung, h thc v cnh v gc trong tam gic.- Bit s dng cc h thc gii cc dng bi tp lin quan.- Rn tnh cn thn trong tnh ton, v hnh chnh xc.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: Hc thuc cc nh l, quy tc .C. Bi tp:I/ Trac nghiem: Cau 1. Ap dung he thc lng vao CHA vuong tai C co ng cao CM , ta co cac he thc ( ien vao dau ... ):( 1 ) AH2 = ...... + ....... ( 4 ) CM2 =....... ........( 2 ) CH2 = ...... ......( 5 ) CH CA = ........ .........( 3 ) CA2 = ...... ......( 6 ) 21CM= ......... + .......... Cau 2..ien vao dau ............Theo nh ngha TSLG cua goc nhon , ta co : sin ECD.... tg E........ cos E........cotg E........ Cau 3. ien vao dau .............Theo he thc lien he canh va goc trong tam giac vuong BCD , ta co :BC = ......... sin ......... = .......... cos ........BC = ......... tg ........... = ......... cotg .......

Cau 4 . Da vao hnh ve : a/ x = ......... b/ y = ......... c/ h = .........Cau 5. at dau , , =vao o vuong :a/ sin 250 sin 160 b/ cos 360cos 420c/ tg 410 tg 450

Giao vien : Le Van Hoa Trng THCS Xuan Lam7D CBAMH c129hy xE CDGiao an day boi dng Toan 9 Nam hoc : 2009 _ 2010d/ cotg 150 cotg 250 e/ sin 700 cos 200 f/ tg 400 cotg 500g/ sin5901h/ 1 cos 360 0i/ tg . cotg 1II/ T luan: Cau 1.Cho ABC vuong tai A ( ABAC), ng cao AH.Biet AB = 15 cm, BH = 9 cm .a/ Tnh AH , AC , BC , AH .b/ Tnh chu vi va dien tch ABC .c/ Tnh so o goc B,C ( tron en phut ) .Cau 2. Cho BCD vuong tai B co BC : BD = 3 : 4 va CD = 40 cm , ve ng cao BE .a/ Tnh BC , BD , EC , ED .b/ Tnh chu vi va dien tch BCD .Cau 3. Cho ABC vuong tai B ( AB BC ) , biet AB 5=BC 6 , ng cao BM = 30 cm .a/ Tnh MA , MC .b/ Tnh chu vi ABC ( o dai tron mot ch co thap phan ) .c/ Tnh so o C ( tron en phut ) .Cau 4. : Cho ADN co AD = 5 , AN = 12 , DN = 13 .a/ Chng minh ADN vuong .b/ Tnh so o cac goc cua tam giac ( tron en phut ) .c/ Tnh o dai ng cao AH ( tron 3 ch so thap phan ) .Cau 5. Cho ABC vuong tai A co AB = 21 , C= 400 . Hay tnh cac o dai :a/ AC b/ BC c/ Phan giac BD ( o dai lam tron 3 ch so thap phan )( ap so : 25,027; 32,670;23,171 )D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap : Phng trnh v t.********************************Giao vien : Le Van Hoa Trng THCS Xuan Lam8Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Ngay day:/ 10 / 2009GiI phng trnh v tA. Mc tiu :- Cng c cho HS cc phng php gii cc dng phng trnh v t.- HS c lm quen vi cc dng bi tp c bn , t p dng vo gii cc dng bi tp tng t.- Rn tnh cn thn trong tnh ton, bin i cn thc.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: n tp nh ngha cn thc, iu kin cn thc c ngha. .C. Bi tp:Dng 1. Phng php nng ln lu thaV d 1: Gii pt :x + 1 x = 13Gii :+ K: x 1 1 x = 13 x(1)Vi x 1 th v tri khng m , pt c nghim th 13 x 0 x 0(1) x- 1 = 169 26x +x2

x2 27x + 170 = 0

(x 10 )( x 17) = 0

x1 = 10 ; x2 = 17V 17> 13 nn pt c nghim l x = 10V d 2 : Gii PT : 3 31 7 2 x x + + Gii :Lp phng 2 v. p dng hng ng thc (a+b)3 = a3+ b3 +3ab(a+b)Ta cx + 1 + 7 x + 3 ( ) ( )31 7 x x + .2 = 8(x+1)(7-x) = 0x1 = -1 ; x2 = 7Dng 2. Phng php a v phng trnh cha du gi tr tuyt i.V d 3 : Gii phng trnh: 2 1 2 1 2 x x x x + + Gii :+ iu kin : x1Ta c 1 2 1 1 1 2 1 1 2 x x x x + + + + Giao vien : Le Van Hoa Trng THCS Xuan Lam9Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010 1 1 1 1 2 x x + + 1 1 x = -(1 x - 1)1 x 0x 2 .Vy 1 x 2.Dng 3. Phng php t n phV d 4: Gii phng trnh:2x2 + 3x + 22 3 9 x x + + = 33 (*)Gii:* 2x2 + 3x +9 + 22 3 9 x x + + - 42 = 0t y = 22 3 9 x x + + (y > 0 v 2x2 + 3x +9 = 23 2722 4x 1 _+ + 1 , 1 ] > 0)Ta c y2 + y 42 = 0 (y 6 ) ( y + 7 ) = 0y1 = 6 ; y2 = -7 (Loi)Suy ra 22 3 9 x x + + = 6 2x2 + 3x 27 = 0 (x 3)(x + 92) = 0x1 = 3 ; x2 = - 92Dng 4.Phng php bt ng thc.V d 6: Gii phng trnh:1 x -5 1 x =3 2 x (1)Gii:+ iu kin : x 1 x < 5x, do 1 x 3 th 32 x > 1 ;1 x +>2 nn v tri ca phng trnh ln hn 3. Vi -1 x < 3th 32 x < 1 ;1 x +< 2 nn v tri ca phng trnh nh hn 3.Vy x = 3 l nghim duy nht.D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap : Cc bi ton v cn bc haiGiao vien : Le Van Hoa Trng THCS Xuan Lam10Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010********************************Ngay day:/ 10 / 2009n tp CC BI TON V CN BC HAIA. Mc tiu :- Cng c cho HS cc bi ton v cn bc hai- HS c lm quen vi cc dng bi tp c bn , t p dng vo gii cc dng bi tp tng t.- Rn tnh cn thn trong tnh ton, bin i cn thc.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: n tp cn bc hai.C. Bi tp:Bi1: a) ( ) ( )2 23 2 1 2 - + - ; b) 3 2 2 +;c) 4 2 3 - d) ( ) ( )2 23 7 5 2 7 - + - ; e) 12 6 3 12 6 3 + + - GV hng dn HS gii mu sau gi HSln bng trnh by li gii cc cu cn li a) = 3 2 1 2 - + - =3 2 2 - +=3 - 1 b) = 2 2 2 1 + + = ( )22 1 + = 2 1 + =2 1 +(v2 > 1)c)= 4 2 3 - =( )23 2 3 1 3 1 3 1 - + = - = -(v 3>1)d)= 3 7 5 2 7 - + - = 3 -7 + 2 7 - 5 =7 - 2e)= 9 2.3 3 3 9 2.3 3 3 + + + - + =( ) ( )2 23 3 3 3 + + -= 3 +3+ 3 -3 = 6Bi 2 : Rt gn a) 318 -32 4 2 162 + + ; b) 248 4 27 75 12 - + + ; c) 80 20 5 5 45 + - - ; d)( )3 2 50 2 18 98 - +; e) ( )227 3 48 2 108 2 3 - + - -Hng dna) = 182;b)= 33;c) = -105;d) = 36; e) = 43 - 2Bi 3 : Tnh :Giao vien : Le Van Hoa Trng THCS Xuan Lam11Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010 a) ( )23 12 18 1 22 2+ - + - ; b) 3 2 3 2 53 2 3 2 6- +- -+ - c) 2 6 2 3 3 3272 1 3- +- +-; d) 7 5 7 5 7207 5 7 5 5- +- ++ - e) 1 14 2 2 4 2 2++ -; f) 5 2 2 5 95 2 10 1--- +Bi4: Rt gn cc biu thc sau :a)( )216 1 4 4 x x + + ;b)( )219 3 93a aa- +-vi a < 3c) 22 4 218x x + +;d)4 2 4 24 4 1 6 9 a a a a - + - - +e)1 - 24x 4x 12x 1- +-;f)22 1 x x + + + 2x +1Bi 5 : Rt gn v tnh gi tr ca biu thcA = 2 22 22 2 2x xxy y x x xy y+-- + - - Vi x 1 ; x y ; v y = 4 2 3 +B = 22 21 1 21 2 1 1a a a aa a a a- + -+ -- + + - vi a = 12C = 1 212 2 x x- ++ - vi x > 0; x 0Bi 6 : Cho biu thc : N = x + 4 x-4 +x-4 x-4 a) Tm iu kin ca x ;b) Rt gn N;c) Tnh gi tr ca x N= 4Bi 7: Gii cc phng trnh :a) 25 x + = x + 1;b) 22 4 x x + + = x -2;c)2 5 x += 5 x;d)1 x-= x -1Bi 8: Rt gn v tnh gi tr biu thc sau : a) A = 5x - 29 6 11 3x xx- +-vix = -3; b) B= ( )3 2 3 2 22 33 2 1+ ++ - ++Bi 9 Tm cc gi tr ca a cc cn bc hai sau c ngha:a) 5a;b)22 5a + ;c) 2a; d)22 a +;e) 8a ; h)22 1 a a +Bi 10Tmx bit:a) 5 4 x;b)2) 1 ( 4 x -6 = 0Bi 11 Rt gn cc biu thc :. / 75 48 300; . / 98 77 0, 5 8. / 9 16 49 .; . / 16 2 40 3. 90a bc a a a d b b b+ + + + Bi 12: Cho biu thc : x-2 x+2 x2 -2x +1 M = ( -). x-1 x+ 2 x +1 2 a) Tm K biu thc M c ngha;b) Rt gn MBi 13 : Cho biu thc :Giao vien : Le Van Hoa Trng THCS Xuan Lam12Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010 x+2 x1 x -1 M = (++): x x-1x+ x + 11-x2a) Tm K biu thc M c ngha; b) Rt gn Mc)Chng minh M>0 vi mi x 0 v x 1.D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap : Hm s bc nht.********************************Ngay day:/ 10 / 2009Hm s bc nht.A. Mc tiu :- Cng c cho HS cc khi nim v hm s.- HS c lm quen vi cc dng bi tp c bn , t p dng vo gii cc dng bi tp tng t.- Rn tnh cn thn trong tnh ton, bin i cn thc.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: n tp khi nm hm s.C. Bi tp: I-TRC NGHIM: 1- Cho hm s y=332+ x. Cu no sau y ng?A. f(-3)=1B. f(0)=3C. f(3)=31 D. f(-1)=2 2- Cho hm s y=f(x)=32+ x. Cu no sau y sai? A. f(-2)=4B. f(1)=25 C. f(4)=1 D. f(3)=3. 3- im A(2;-1) thuc th hm s no?A. y=2x-3B. y=-xC. y=12xD. y=2x. 4- im no sau y thuc th hm s y=24+ x?A. ()211 ; 2 B. ()412 ; 1 C. (-4;3)D. C ba im. 5-Ni mihm s ct 1 vi mnh cho ct 2 c kt qu ng.A. 321 x ya.X/ s thc x tha mn 3 1 xGiao vien : Le Van Hoa Trng THCS Xuan Lam13Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010B. x y 1b. X/ s thc x tha mn 121 xC.x x y + + 3 1c. X/ s thc xD.xxy ++ 11 21d. X/ s thc x tha mn1 x II-T LUN: Bi 1.Cho hm s x x f y43) ( . Tnh: f(-5) , f(-4) , f(-1) , f(0) , f()21, f(1) , f(2) , f(4) , f(a) , f(a+1).Bi 2.Cho hm s y= f(x) = 52x. Tnh:f(0), f(-1), f(31), f(25), f(a), f(a+b).Bi 3. Cho hm s y = g(x) = 22x . Tnh: g(21) , g(31) , g(-2) , g(a) , g(a-b).Bi 4. V th cc hm s:a) y=x b) y=-x c) y=x43 d) y=-0,8x.Bi 5.Gi (d) l th ca hm s y=f(x)=2x+1. a) Lp bng gi tr ca hm s f vi cc gi tr ca x l : -2 ; -1 ; 0 ; 1 ; 2 . b) im no trong cc im sau y thuc th (d)?A(-3;-5) ; B(-1;-1) ; C(21;2) ; D(1;4) ; E(3;7) . c) Tm thm 3 im thuc (d) & 3 im khng thuc (d).Bi 6: cho hm s f(x) = ax5 +bx3 +cx -5 (a,b,c l hng s ).Cho bit f(-3) = 208. tnhf(3)Gii:Ta c f(-3)= a(-3)5 + b(-3)3 +c(-3) -5; f(3) = a35+ b33 +3 c-5 Nn f(-3) + f(3) = -10 .Do 208 + f(3) = -10. Vy f(3) = -10- 208 = - 218Bi 7: Tm gitr ln nht ca hms :a) y = -2x2 + x 1b) y = 4 212 3+ + +x x xxGii:a) y = -2x2 + x -1 = -2(x2 x) 1 = -2[x2 -2.41x + (41)2 - (41)2]- 1= -2 (x- 41)2 - 8787 vi mi xHm s tgi tr ln nht bng -87 khi x =41b) y =4 212 3+ + +x x xx= 4 21) 1 )( 4 2 (12 2+ + + +x x x x xx = ) 1 (313 ) 1 (12 + xxHmstgi tr ln nht bng 31, khi x = 1Giao vien : Le Van Hoa Trng THCS Xuan Lam14Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap : th hm s y = + b (a 0).********************************

Ngay day: 27/ 10 / 2009n tp v th hm sA. Mc tiu :- Cng c cho HS cc khi nim v hm s bc nht , hm s y = ax + b(a0). ng thng song song, ng thng ct nhau.- HS c lm quen vi cc dng bi tp c bn , t p dng vo gii cc dng bi tp tng t.- Rn tnh cn thn trong tnh ton, v th hm s.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: n tp khi nm hm s bc nht , hm s y = ax + b(a 0). ng thng song song, ng thng ct nhau.C. Bi tp:I/ Trac nghiem:1/ Ham so1. 4 y m x + la ham so bac nhat neu:A. 1 B. 1 C. 1 D. m m m m R > 2/ iem M(-5;1) thuoc o th ham so y=ax+2 neu

1 1A. 6 B. 4 C. D.5 5a a a a 3/ Cho cac ham so: 30, 3 , , 3 , 24y x y x y x y x Neu nhan xet tnh , ( hoac S) cua cac cau ket luan sau:A.Cac ham so a cho eu ong bienB.Cac ham so a cho eu xac nh vi moi so thc xC. o th cac ham so tren eu la ng thang i qua goc toa o OD. o th cac ham so nay eu cat nhau tai iem O(0;0)II/ T luanBI 1:Ve o th ham so sau:Giao vien : Le Van Hoa Trng THCS Xuan Lam15Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010a) y = 2x; c) y =- 2x + 1b)y =2x + 3 d ) y =23x - 1BI 2: Xac nh ham soa) Cho hm s y = 3x + b, bit rng vi x = 4 th hm s c gi tr 11. Hy xc nh hm s cho.b) Cho hm s y = ax + 3, bit rng vi x = 4 th hm s c gi tr 19. Hy xc nh hm s choc) Cho hm s y = ax + 5, bit th hm s i qua im M ( -1; 3 )d) Cho hm s y = -2x + b, bit th hm s i qua im N (1; 2 )BI 3: a) V th hm s (d1) y = -x + 2 v (d2): y = x 2 trn cng mt mf ta b) Gi A l giao im ca hai th trn. Tm ta ca im A.c) Gi Bv C ln lt l giao im (d1) v (d2) vi trc tung. Tm ta ca B v Cd) Tm chu vi v din tch ca ABCBI 4:a) V th cc hm s sau trn cng mt mt phng ta y = 2x (1); y = 0,5x (2); y = -x + 6 (3)b) GI giao im ca ng thng c phng trnh (3) vi hai ng c phng trnh (1) v (2) theo th t A v B. Tm ta ca hai iem A v BBI 5: Vi gia tr nao cua m th ham so sau la hs bac nhat? 1) ( 2) 3 ) 53a y m x b y xm + +BI 6: Neu tnh bien thien cua ham so sau: ) ( 3 2) 1 ) (2 5) 5 a y x b y x + BI 7: Vi gia tr nao cua m th:a) Ham so (3 2 ) 5 y m x m +ong bien?b) Ham so 2 11 5y xm + nghch bien ?BI 8: Tren mat phang toa o Oxy, cho cac iem A(1;3), B(-2;4),C(2;-1). D(0;5).Tnh o dai cac oan thang AB, AC, AD, BC,BD, CD ( 1 n v o dai bang 1cm)BI 9: Tm k cua ham so y=kx+1, biet rang o th cua ham so song song vi ng thang y=5-2xBI 10: Cho ham so y=ax+b . Tm a vab, biet o th ham so qua iem A(-5;2) va song song vi ng thang y=3+6xBI 11: Cho ham so y=2x+b. Tm b biet o th ham so cat ng thang y= 5+2x tai 1 iem tren truc tung va xac nh ham so oBI 12: Cho ham so y =ax+1. Hay xac nh he so a biet o th ham so cat ng thang y= -6x+4 tai iem co hoanh o bang -2Giao vien : Le Van Hoa Trng THCS Xuan Lam16Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010BI 13: Cho hai ham so bac nhat: y=(5m-2)x +4 (d) va y= 3x+k (d).Tm ieu kien cua m va k e (d) va (d): a/(d) va (d) cat nhaub/(d) va (d) song song c/(d) va (d) trung nhauD. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap : Hm s.********************************Ngay day: / 11 / 2009n tp : ng thng song song - ng thng ct nhauA. Mc tiu :- Cng c cho HS v ng thng song song, ng thng ct nhau.- HS c lm quen vi cc dng bi tp c bn , t p dng vo gii cc dng bi tp tng t.- Rn tnh cn thn trong tnh ton, v th hm s.B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: n tp ng thng song song, ng thng ct nhau.C. Bi tp:A. n l thuyt :? Nu iu kin hai ng thng song song , ct nhau . Vit cc h thc tng ng ?Tng qut :Cho ng thng (d) c phng trnhy = ax + b ( a 0 ) v ng thng (d) c phng trnh y = ax + b( a 0) . + (d) v (d) song song vi nhau a = a v b b .+ (d) v (d) ct nhau a a. Nu b = b th (d) ct (d) ti im trc tung c to l ( 0 ; b)B. Bi tp :1.Bi tp 20 ( SBT - 60) HD: Theo bi ra ta c khi1 2 x + th3 2 y +thay vo cng thc ca hm s ta c : 3 2 (1 2) 1a(1+ 2) 2 2 a + + + +(1 2) 2(1 2) 2 a a + + Vy hm s cn tm l : y =2 1 x +2.Bi tp 21 ( SBT - 60) HD: Theo bi ra ta c : Giao vien : Le Van Hoa Trng THCS Xuan Lam17Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010+ th hm s y = ax + b ct trc tung ti im c tung bng 3 vi x = 0 th y = 3 . Thay vo cng thc ca hm s ta c : 3 = a . 0 + b b = 3 . + th hm s y = ax + b ct trc honh ti im c honh bng - 2 vi x = -2 th y = 0 . Thay vo cng thc ca hm s ta c : 0 = a . ( -2) + b - 2a + 3 = 0 ( v b = 3 ) a = 32Vy hm s cn tm l : y = 332 x +3.Bi tp 23 ( SBT - 60) HD:a) Gi ng thng i qua A ( 1 ; 2) v B( 3 ; 4) l y = ax + b - V ng thng y = ax + b i qua A ( 1 ; 2 ) . Thay to ca im A vo cng thc ca hm s ta c : 2 = a.1 + b ( 1) a + b = 2 b =2 - a ( 3) - V ng thng y = ax + b i qua im B( 3 ; 4) . Thay to ca im B vo cng thc ca hm s ta c : 4 = a.3 + b ( 2) Thay (3) vo(2) ta c : (2) 3a + ( 2 - a ) = 4 3a - a = 4 + 2 2a = 6 a = 3 Vy h s a ca ng thng i quaA , B l : a = 3 .b) V th ca hm s y = ax + b i qua A ; B theo phn (a) hm s c h s gc l 3 hm s c dng y = 3x + b . Li c b = 2 - a vi a = 3 ta c b = 2 - 3 = - 1 . Vy hm s cn tm l : y = 3x - 1 . 4.Bi tp 24 ( SBT - 60 ) a) ng thng y = ( k + 1) x + k i qua gc to O( 0 ; 0 ) thay x = 0 ; y = 0 vo cng thc ca hm s ta c 0 = ( k + 1 ) .0 + k k = 0 . Vy vi k = 0 th ng thng i qua gc to .b) ng thng y = ( k+1) x + k ct trc tung ti im c tung l 1 2 Vi y= 1 2 ; x = 0 thay vo cng thc ca hm s ta c : 1 2 ( 1).0 1 2 k k k + + Vy vi k = 1 2 th ng thng y = ( k + 1)x + k ct trc tung ti im c tung l 1 2 . c) ng thng (1) song song vi ng thng y = ( 3 1) 3 x + + ta phi c : 1 0 11 3 1 3 33 3k kk k kk k + + + ' ' Vy vi k =3th (1) song song vi ng thng y = ( 3 1) 3 x + +.5.Bi 5 : Tm m ng thng y = ( 2m 3 ) x + 3 i qua im A ( -2 ; 3 ) Giao vien : Le Van Hoa Trng THCS Xuan Lam18Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010V th hm s va tm c . 6.Bi 6:Cho ng thng y = ( m + 2 ) x 2m 3 . a) Tm m ng thng trn song song vi ng thng y = 3x + 1 . b) Tm m ng thng trn vung gc vi ng thng y = -2x + 1 7.Bi 7:Cho hm s : y = 3x + 1 ( d) a) V th hm s v tm m im B ( m ; 2m 3 ) thuc th hm s . b) Tm k ng thng y = 3kx 2k + 1 song song vi th hm s trn . c) Tma th hm s trn ng quy vi hai ng thng y = x + 2 v y = ( 2a 1 )x + 3 D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap : Hnh hc********************************Ngy dy:S XAC NH NG TRON . TNH CHAT OI XNG CUA NG TRONA. Mc tiu :- Cng c cho HS khi nim v ng trn , im thuc , khng thuc ng trn . Mi quan h gia ng knh v dy.- Cng c cho hc sinh cch xc nh mt ng trn i qua hai , ba im khng hng hng . - Chng minh cc im thuc ng trn . - Rn k nng chng minh im thuc ng trn theo nh ngha . B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: Hc thuc cc nh l .Giao vien : Le Van Hoa Trng THCS Xuan Lam19Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010C. Bi tp:A/ Trac nghiem: Khoanh tron ch ng trc cau ma em chon la ung nhat. *Cau 1:Cho hai iem phan biet A, B. Phat bieu nao sau ay ung?A. Co duy nhat mot ng tron i qua hai iem A, B, chnh la ng tron ng knh AB.B. Khong co ng tron nao i qua A, B v thieu yeu to.C. Co vo so ng tron i qua A, B vi tam cach eu A, B.D. Co vo so ng tron i qua A, B vi tam thuoc ng thang i qua A va B.*Cau 2:Cho oan thang AB = 5cm.Hoi dng c bao nhieu tam giac vuong co AB la canh huyen va mot canh goc vuong co o dai 4cm?A.1 B.2 C.4 D. Vo so*Cau 3: Cho 3 iem A, B, C khong thang hang. Phat bieu nao sau ay la sai?A.Co mot ng tron duy nhat i qua ba iem A, B, CB.ng tron i qua ba iem A, B, C goi la ng tron ngoai tiep tam giac ABC.C.ng tron i qua ba iem A,B,C co tam la giao iem cua hai trong ba ng trung trc cua cac oan thang AB, BC, CA.D.Ca ba cau tren deu sai. *Cau 4 : Cho ng tron (O ; R) va cac iem M, N, P thoa man OM< R< ON OP. Ket qua nao sau ay cho biet v tr cua cac iem M,N,P oi vi ng tron (O) ?A. M ben trong (O), N va P ben ngoai hoac thuoc (O).B.M ben ngoai ng tron (O), N va P ben trong ng tron (O)C.M ben trong (O), N va P ben ngoai (O). D.Ca ba cau tren eu sai. *Cau 5 : Cho ng tron (O ; 5cm) . iem M thuoc (O) va N la iem sao cho MN = 6cm. V tr cua N oi vi ng tron (O) la :( Chon cau ung)A. N trong (O). B. N ngoai (O).C. N trong hoac thuoc (O). D. Khong ket luan c.*Cau 6:Tam giac co o dai ba canh la 8cm, 15cm, 17cm th ban knh ng tron ngoai tiep tam giac ay co o dai la: A. 7,5cm B.8,5cm C.12,5cm D.16cm. *Cau 7: Hnh tron tam ( O; 5cm) la hnh gom toan the cac iem cach iem O co nh mot khoang d vi :A. d = 5cm B.d < 5cm C.d 5cm D. d 5cmGiao vien : Le Van Hoa Trng THCS Xuan Lam20Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010B/ T luan: Bai 1.Cho t giac ABCD co hai ng cheo AC va BD vuong goc vi nhau. Goi E, F, G, H lan lt la trung iem cac canh AB, BC, CD, DA. Chng minh bon iem E, F, G, H cung nam tren mot ng tron. Xac nh tam cua ng tron ay. Bai 2.Cho tam giac eu ABC. Goi M, N, P lan lt la trung iem cac canh AB, AC, BC. Chng minh bon iem B, M, N, C cung nam tren mot ng tron. Xac nh tam cua ng tron ay. Bai 3. Cho ng tron (O), ng knh BC va mot iem A nam tren ng tron ay.a/ Chng minh : tam giac ABC vuongb/ Ve D oi xng vi A qua BC. Chng minh : tam giac BDC vuongc/Goi H la giao iem cua AD va BC. Chng minh: AH2 = DH2 =HB . HC Bi 2: Cho tam gic ABC cn ti A , ng cao AH = 2cm , BC = 8cm . ng vung gc vi AC ti C ct ng thng AH D a. Chng minh rng cc im B, C thuc ng trn c ng knh AD. b.Tnh di ADBi 4: Cho (O;5cm) v mt dy cung AB di 6cm. Gi I l trung im ca AB . Tia OI ct ng trn ti M. Tnh di dy cung MABi 5: Cho nhn ABC , cc ng caoBD v CE ct nhau ti H a . Chng minh rng : B,E, D ,C cng thuc mt ng trn b. Chng minh rng : A, D ,H ,E cng thuc mt ng trn c . Chng minh rng : BC> DE, AH > DEBi 6 : Cho ng trn (O, R) , A v B thuc ng trn (O) sao cho 090 AOB .Gi M l trung im ca ABa. Chng minh rng:OM AB b. Tnh di AB ,OM theo RBi 6 : Cho ng trn (O),dyAB = 48 cm v cch tm 7cm . Gi I l trung im ca AB . Tia IO ct ng trn ti C.a. Chng minh ABC l tam gic cn.b. Tnh khong cch t O n BCD. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap :Hm s.********************************Ngy dy:n tp hm s bc nhtA. Mc tiu :- Tip tc n tp cho HS kin thc v HS bc nht.Giao vien : Le Van Hoa Trng THCS Xuan Lam21Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010- Luyn cho HS bit cch lp phng trnh ng thng i qua 2 im, xc nh to giao im ca 2 ng thng.- Rn k nng tnh ton chnh xc. B. Chun b ca GV - HS :- GV : Son bi su tm ti liu , gii cc bi tp trong sch bi tp , chn la mt s bi tp ph hp . - HS: Hc thuc cc tnh chtC. Bi tp:Bi 1: Phng trnh /t i qua 2im B(1;4) v C(-2;3) l:A. y = 3431 x B. y = x + 11C. y = 31131+ xD. y = - 2x + 311Chn CBi 2: Cho 3 im A(3;-1) B(2;1),C(0;1). Phng trnh ca/t (d) i qua C v // vi /t AB l.A. y = -2x + 1B. y = x + 1C. y = 3x + 1 D.y= -x + 1Chn ABi 3:Trong mp ta Oxy cho cc im A(0;5); B(-3;0); C(1;1);M(-4,5;-2,5) .a) Chng minh rng A;B;M thnghng v A;B;C khng thng hng b) Tnh din tch tam gic ABC.Gii : a) PT ng thngi qua2im A,B l: y = 35x + 5 .+)Ta c :-2,5 = 35.(-4,5)+ 5 vy im M thuc vo /ty = 35x + 5 .Hay A,B,M thng hng.+) Ta c 135.1 + 5 ,nn im C khng thuc vo ng thngy = 35x + 5 .Hay A,B,C khng thng hngb) Ta c : AB2 = 32 +52 = 34AC2 = 12 +42 = 17Giao vien : Le Van Hoa Trng THCS Xuan Lam22Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010BC2 = 42 + 12= 17 AB2 = AC2 + BC2 nn tam gic ABC vungcn ti C.SABC = 21CA.CB =21CA2 = 8,5 (vdt) Bi 4: Trn mp ta cho 3im : A(- 3 2 ;0); B(-2;0) v C(0;2) .a) Tm cc hm s m th ca n l ng thng AC, ngthng BC.b) Tm s o cc gc catam gic ABC.Gii:a) Hm s c th l /t BC l : y =31x + 2 v hm s c th l /t : y = x + 2b) Ta c :tgCAB = 313 22 OACO CAB300tgCBO = 122 CBCO CBO450ABC = 1350 Vycc gc ca ABC cs o l :A = 300; B = 1350 ;C = 150 Bi 5 :a) cho 4im A(0;-5), B(1;-2), C(2;1), D(2,5;2,5) . CMR bn im A,B,C,D thng hng b) Tm x sao cho 3 im A(x;14) , B(-5;20), C(7;-16) thng hng Bi 6:Xc nh k cc ng thng sau ng quy :(d1):y =2x +3; (d2):y =-x -3; (d3):y =kx -1Bi 7: a) V trn cng h trc ta cc th hm s : y = x + 2 (d1);y = 21x + 1 (d2)b) Gi A l giao im ca (d1) v (d2). Tmto giao im Ac) Gi (d3) l /t iqua K(0;25) song song vitrc honh. ng thng (d3) ct cc ng thng (d1) v (d2) theo th t ti B v C. Tm ta ca B vC ritnh din tch tam gicABCH ng dn: a)Giao vien : Le Van Hoa Trng THCS Xuan Lam23Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010b) Honh ca A l nghim ca p/t :x + 2 = 21x + 1 xA = 32Tung ca A l : yA = 32 + 2 = 34Vy ta ca A(32;34)c) Honh giao im ca (d1) v (d3) l nghim ca p/t :25= x + 2 xB = 21 B(21;25)Honh giao im C l nghim ca p/t:12125+ x xC = -3 C(-3 ; 25)Din tch tam gic ABC l:SABC = 21BC.AH = 21(xB xC).( 25- yA) = 21(21+3)( 25-34) = 2449(vdt)D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap Gii h phng trnh. ********************************Giao vien : Le Van Hoa Trng THCS Xuan Lam24Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Ngy dy:Gii h phng trnhbng phng php th - phng php cng A.. Mc tiu : - Rn luyn k nng gii h phng trnhbng phng phpth , ph-ng php cng .C k nng tho rt n v th vo phng trnhcn li , cng cc v ca 2 phng trnh.- Gii thnh tho cc h phng trnhbc nht hai n bng phng phpth , lm mt s dng bi tp lin quan n xc nh h s ca h phng trnhbc nht hai n . - C k nng bin i tngng h phng trnhbc nht hai n bng quy tc th . B. Chun b ca thy v tr : - Son bi , c k bi son , gii bi tp la chn bi tp cha . - Bng ph ghi quy tc th v cc bc gii h phng trnhbc nht hai n bng quy tc th, quy tc cng.C. Bi tp:Bi tp 1. Gii cc h phng trnh sau bng phng php th :a) ' +7 23 3y xy x b) ' +0 3 28 5 2y xy xc) ' + +4 26 3 4y xy xd) ' +3 2 32 3 2y xy x e) ' +5 , 1 2 5 , 13 5 , 0 3 , 0y xy xp n : p n :a) H phng trnh c nghim duy nht (x; y) = (2; -3)b) H phng trnh c nghim duy nht (x; y) = (1,5; 1)c) H phng trnh c nghim duy nht (x; y) = (3; -2)d) H phng trnh c nghim duy nht (x; y) = (-1; 0) e) H phng trnh c nghim duy nht (x; y) = (5; 3)Bi tp 2. Gii cc h phng trnh sau bng phng php th :Giao vien : Le Van Hoa Trng THCS Xuan Lam25Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010a) ' + 2 2 21 3 2y xy xb) ' +2 2 62 2 3 5y xy xp s: a) x = 86 2 ; y = -42 1+b) x = 66 ; y=-22Bi tp 3 : Gii h phng trnh sau bng phng php cng i s :a) ' + 7 3 64 2 5y xy xb) ' + 5 6 41 1 3 2y xy xc) ' 313321 0 2 3y xy xd) ' + + + +5 ) ( 2 ) (4 ) ( 3 ) ( 2y x y xy x y xe) ' + + + 3 ) 1 ( 2 ) 2 ( 32 ) 1 ( 3 ) 2 ( 2y xy xf) ' + 54 311 1y xy xBi tp 4: Gii h phng trnh bng phng php t n s ph a, ' + + + 2 ) 2 3 ( 7 ) 2 3 ( 4) 2 3 ( 5 4 ) 2 3 ( 2y xy x Gi : C th t 3x-2=a;3y+2=b b, '+ ++2 13 25332353 24y x y xy x y x

Gi : t by xay x+ 31;..3 21iu kin x 1,5yv x -y/3Giao vien : Le Van Hoa Trng THCS Xuan Lam26Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010 c, ' +++ ++ 412235 , 41527y x y xy x y xBi tp 5.Giih phng trnh sau a, ' + +1 2143431 01 153y xy x b,'++++1 212111121 518y xy x c, 5 282 13 11, 52 1x y x yx y x y + +'+ + + d, 521 2 12 1 1x yy xx y+ ' +++ e, ' +13 45 6 6y xx y y x D. Dan do ve nha- Ve nha xem lai cac dang bai tap a cha.- T su tam them cac dang bai tap tng t e luyen giai. - Tuan sau: On tap Hnh hc : ********************************Ngy dy: n tp : d hiu nhn bit tip tuyn ca ng trnA. Mc tiu : - Ren luyen k nang nhan biet tiep tuyen cua ng tron.- Ren luyen k nang chng minh, k nang giai bai tap dng tiep tuyen.- Phat huy tr lc cua HS.B. Chun b ca thy v tr : GV : - Thc thang, compa.HS : - Thc thang, compaC. Bi tp:I) L thuyt:Giao vien : Le Van Hoa Trng THCS Xuan Lam27Giao an day boi dng Toan 9 Nam hoc : 2009 _ 2010Du hiu 1: Nu 1 /t v 1 ngtrn ch c 1 imchung th ng thng l tiptuyn ca ng trn.Du hiu 2: Nu 1 /t i qua 1 im ca ng trn v vung gcvibn knh i qua im th ngthng y l 1 tip tuyn ca ng trn.II) L thuyt:Bi 1) Cho VABC vung ti A ( AB