Vector 3 Axis

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vector in 3D notes Maths concepts and application.

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  • - 1 - www.focus-physics.com

    3.1

    YY

    X

    X Z

    Z

    XX , YY , ZZ X Y Z O X Y Z ( Origin ) P 3 P P ( x , y , z ) P(3,4,4) XY , YZ XZ P(3,4,4) (QR,RS QS)

    X

    Y

    Z

    P 3,4,4

    R

    Q

    S

    P(3,4,4) XY Q 3,4,0 YZ R(0,4,4) XZ S(3,0,4)

  • - 2 - www.focus-physics.com

    1 1 1P(x , y ,z ) 2 2 2Q(x , y ,z )

    2 2 22 1 2 1 2 1PQ x x y y z z

    2 2 2QR 0 3 4 4 4 0

    9 0 16 25 5 2 2 2RS 3 0 0 4 4 4

    9 16 0 25 5 2 2 2QS 3 3 0 4 4 0

    0 16 16 32 4 2

    3.2

    (1) (Scalar Quantity) (2) (vector quantity ) A B

    A

    B

    A B

    A

    B

    ABAB

    AB

    AB AB

  • - 3 - www.focus-physics.com

    AB A B A B AB AB A B A B () AB AB AB

    u u

    A

    B

    A B

    A

    B

    u

    u

    u

    u

    u u v u v

    u

    v

    w

    u

    v

    w

    u

    v

    w

    u v u v u v u = v

    u

    v

    w

    u

    v

    w

    u

    v

    w

  • - 4 - www.focus-physics.com

    u u u u - u

    u

    u v

    v

    w

    w

    1 10 (1) 50 009 (2) 65 040 (3) 30 150 (4) 40 300 0o 360o 100o three figure system

    OA 50 009 OB 65 040 OC 30 150 OD 40 300

  • - 5 - www.focus-physics.com

    ( 0o 360o 100o three figure system ) (1) 120 (2) 30 120o (3) 60 225o (4) 10 075o

    N

    120

    A

    B

    N

    A

    B

    120

    30

    N

    A

    B

    225

    60

    N

    A

    B75

    10

    1 2 3 4

    5 5 50

    v,u,w vuw v

    u w u w v

    u

    w v

  • - 6 - www.focus-physics.com

    A

    B

    CS

    AB BC AC

    AB BC

    AC

    P

    QR

    RS

    QR

    PQ

    PS

    PQ QR RS PS

    (jew vector) 0 AB BC CA AA 0

    A

    B

    C

    AB BC CA AA 0

    AB BC

    CA

    PQ QR RS SP PP 0

    SP

    QR

    RS

    QR

    PQ

    SP

    PQ QR RS SP PP 0 v,u )v(uvu

    vu u v

    u

    v

    u

    v

    u v

    u

    2u

    2u

  • - 7 - www.focus-physics.com

    2 u 2 u u ( -2 u ) 2u u 1 u a ( ) u a a u

    1. a = 0 a u = 0 2. a > 0 a u a u

    u 3. a < 0 a u a u

    u

    1 u v , a b

    1. a u 2. a(b u ) = (ab) u 3. a( u + v ) = a u + a v 4. (a+b) u = a u + b u

    2 0u 0v u v a

    vau 3 0u 0v , u v Rb,a

    0vbua a = 0 b = 0

  • - 8 - www.focus-physics.com

    PQ u,v,w

    u

    v

    P

    Q

    1

    u

    v

    w

    P

    Q 2 PQ u v PQ u v w

    u

    v

    wP

    Q 3 P

    Q

    u

    w

    v

    4 PQ u v w PQ u v w ( ) 1. 1.1 () - A B B C AC P Q Q R R S PS

    A

    B

    CS

    AB BC AC

    AB BC

    AC

    A B B C AC

    P

    QR

    RS

    QR

    PQ

    PS

    PQ QR RS PS

    P Q Q R R S PS

    - OB OC BC

  • - 9 - www.focus-physics.com

    1.2 AB CB A B B C AC 1 1. A B B C AC

    2. A B B C C D AD

    3. A B B C C D D E AE 4. AB BC CD DE EA AA 0 2 () 1. AB CB AC 2. AB CB CD AD 3. AB BC DC AD 4. AB CB CD ED EA AA 0 3 () 1. OB OA AB 2. OC OB BC 3. AC AB BC 4. EC ED DC 4 . AB , BD , CA , DB , AF , FA , AE EA a, b, c, d, e f

    A

    B C

    D

    E

    F

    a

    b

    c

    e

    c

    d

    f

    AB a BD b c a f CA b a c f

  • - 10 - www.focus-physics.com

    DB b c f a DB b c f a AF f e a b c e f c d FA f e e a b c f c d AE f c a b 2c f e d EA f c a b 2c f e d 5. u

    u

    1. 2u 2. 3u 3. 0u

    1 2u 2 3u 3 0

    C AB

    O

    m n

    vu

    w

    nu mvwm n

    2 2B x , y 1 1A x , y

    m n

    C x, y

    2 1mx nxx

    m n

    2 1my nyym n

  • - 11 - www.focus-physics.com

    1. w u v

    u v

    w

    2 3

    1

    vu

    w

    1 4

    2

    3u 2v 3u 2v

    w3 2 5 5

    4u 1v 4u vw

    4 1 5 5

    vu

    2 5

    3

    w

    u

    w

    v

    1 3

    4

    5u 2v 5u 2v

    w5 2 7 7

    3u 1v 3u vw

    3 1 4 4

    2. ABCD A 1,2 AB 9 i 4 j, AD i 5 j C 1. 7,11 2. 8,11 3. 9,11 4. 8,9

    A 1,2 B

    C a,bD

    AB 9 i 4 j

    AD i 5 j AC

    AC AB AD AC 1 9 i 5 4 j 8i 9 j

    C a,b a 1 89b 2

    a 1 8 a 7 b 2 9 b 11 7,11

  • - 12 - www.focus-physics.com

    3. ABCD P Q AB AQ:QB 2:3 u AB v AD PQ

    1. 1 u 3v6

    2. 1 7u 3v6

    3. 1 u v10

    4. 1 u 5v10

    u AB v AD

    BA

    CD

    u

    v

    32

    P

    Q

    1 2

    PQ CA AB2 5

    1 2

    AC u2 5

    1 2u v u

    2 5

    1 1u v10 2

    1u 5v

    10

    4. ABC E CE 2BA BE aCB bCA a,b b a 1. -1 2. 2 3. 3 4. 5

    CE 2BA BE aCB bCA

    BE BC CE CB 2BA CB 2 BC CA CB 2 CB CA CB 2CB 2CA 3CB 2CA a 3,b 2 b a 2 3 5

  • - 13 - www.focus-physics.com

    5. ABCD M, N BC CD u AM v AN AB

    1. 3 1u v2 2

    2. 3 u v2

    3. 2 1u v3 2

    4. 4 2u v3 3

    ABCD M, N BC CD u AM v AN

    A B

    CD

    u

    v M

    N

    AB u MB..... 1 AB v NC CB

    1AB v AB 2MB2

    1 1MB AB v...... 24 2

    (2) (1)

    1 1

    AB u AB v4 2

    1 1

    AB AB u v4 2

    3 1AB u v4 2

    4 2AB u v3 3

  • - 14 - www.focus-physics.com

    6. AB P AB AB C PA,PC PB

    P

    AC

    B

    1. PC 4 PA PB 2. PC 2 PA PB 3. 2PC PA PB 4. 4PC PA PB 5. 1. 4.

    P

    AC

    B1 1

    PBPA

    1PB 1PBPC

    1 1

    2PC PA PB 3. 7 . [ . / 2551] ABCD M N BC CD

    BM:MC = DN:NC =1:2 AC AM AN

    A B

    CD N

    M

    1 2

    2

    1

  • - 15 - www.focus-physics.com

    A

    CD N1 2

    1

    A B

    C

    M

    2

    1

    2

    2AD 1ACAN

    2 1

    2AB 1ACAM

    2 1

    3AN 2AD 1AC .... 1 3AM 2AB 1AC .... 2 1 2

    3AN 3AM 2AC 2AB 2AD 3AN 3AM 2AC 2 AB AD BC AD

    3AN 3AM 2AC 2 AC

    3AN 3AM 4AC

    3 3AN AM AC4 4

    3 3 6 1.54 4 4

    8. ABCD M AD 1AM AD5

    N AC 1AN AC6

    MN aAB bAD a b

    1. 215

    2. 15

    3. 13

    4. 1

    A

    B

    CD

    11

    4

    5M

    N

    1AM AD

    5 1AN AC

    6

    MN AN AM

  • - 16 - www.focus-physics.com

    1 1AC AD6 5

    1 1AB AD AD6 5

    1 1aAB bAD AB AD6 30

    1 1 2a b6 30 15

    9. ABC D AC F BC 1 1

    AD AC , BF BC4 3

    DF aAB bBC ab

    A

    D

    CB F

    1

    1 2

    3

    DF DC CF

    3 2 3 2AC CB AB BC BC4 3 4 3

    3 3 2AB BC BC4 4 3

    3 1AB BC aAB bBC4 12

    a 3 12 9b 4 9

  • - 17 - www.focus-physics.com

    10. A a,b ,B 4, 6 C 1, 4 ABC P

    AB A 35 A B CP i 2 j

    a b

    C 1, 4

    A a , b

    B 4 , 6

    P x , y

    3

    2

    C P i 2 j

    2 2B x , y 1 1A x , y

    m n

    C x, y

    2 1mx nxx

    m n

    2 1my nyym n

    x 1 1

    CPy 4 2

    2a 12 25

    2b 18 2

    5

    x 1 1y 4 2

    2a 12 10 2b 18 10

    x 2, y 2 a 1 b 4

    a b 1 4 3

    11. ABCD M AD 1AM AD5

    N AC 1AN AC6

    MN aAB bAD a b

    1. 215

    2. 15

    3. 13

    4. 1

  • - 18 - www.focus-physics.com

    A

    B

    CD

    11

    4

    5M

    N

    1AM AD

    5 1AN AC

    6

    MN AN AM

    1 1AC AD6 5

    1 1AB AD AD6 5

    1 1aAB bAD AB AD6 30

    1 1 2a b6 30 15

    12. u v PR 3u 1. QR 2. PS 3. SQ

    uv

    P

    Q

    R

    S 1. QR 2u 2. PS 3u v 3. SQ 2u v 13. ABC AD BA a BD b CA

    A

    B CD

    a

    b 1. a 2. a b 3. a 2b 4. a 2b ( 3)

  • - 19 - www.focus-physics.com

    2 u v 1. u v u kv k 1.1 k 0 1.2 k 0 1.3 k 0 2. u v au bv a 0 b 0

    1. u 0 v 0 x u v

    1.1 2 22x x u v xv 6x 2 x u u v

    2 22x x u v xv 6x 2 x u

    2 22x x u 6x 2 x u xv v

    23x 7x 2 u x 1 v

    2

    x 1u v

    3x 7x 2

    u v

    2

    x 10

    3x 7x 2

    x 10

    3x 1 x 2

    1

    1

    32

    1x , 1 ,23

  • - 20 - www.focus-physics.com

    1.2 2x 1 u 3v v 5 x u u v

    2x 1 u 3v v 5 x u

    2x 1 u 5 x u v 3v

    2x x 6 u 2v

    2

    2u v

    x x 6

    2

    20

    x x 6

    2x x 6 0 x 2 x 3 0 x 3,2

    1.3 22x 8 u xv 3v x u u v

    22x 8 u xv 3v x u

    22x 8 u x u 3v xv

    22x 8 x u 3 x v

    2

    3 xu v

    2x 8 x

    u v

    2

    3 x0

    2x 8 x

    2

    x 30

    x 2x 8

    x 30

    x 4 x 2

    2 3 4

    x , 3 3,4

  • - 21 - www.focus-physics.com

    3.3 . AB 1 2A(x , y ) 2 2B(x , y )

    AB 2 12 1

    x x

    y y

    2 1x x a 2 1y y b

    AB ab

    x

    y

    A 4,6

    B 3,4

    C 6, 6 D 6, 5

    E 4, 2

    O 0,0

    4 0 4OA6 0 6

    3 0 3OB4 0 4

    6 0 6OC6 0 6

    4 6 2DE

    2 5 3

  • - 22 - www.focus-physics.com

    1. PQ P Q (1) 3,2P 6,8Q (2) 4,3P 1,1Q

    (1)

    3

    6

    36

    28PQ

    (2)

    3

    4

    41

    )3(1PQ

    2.

    () 1 (1,3) (4,8) (4 1) i 8 3 j 3i 5 j

    2 (3,5) (8,2) (8 3) i 2 5 j 5i 3 j 3 ( 4,2) (3,5) ( 3 4 ) i 5 2 j i 3 j 4 (0,0) (4, 3) (4 0) i 3 0 j 4i 3 j 5 (0,0) (4,4) (4 0) i 4 0 j 4i 4 j

    3. 2,6A 3,8B D ABCD C

    (1) 1,1C (2) 4,3C (3) 6,5C (4) 7,1C

    D y,x

    (1)

    1y

    1xCD

    23

    68AB

    1y

    1xCD

    1

    2AB

    ABCD

    1

    2

    1y

    1x

  • - 23 - www.focus-physics.com

    x 1 = 2 y + 1 = - 1 x = 3 y = - 2 D (3,-2)

    (2)

    4y

    3xCD

    1

    2AB

    ABCD

    1

    2

    4y

    3x

    x + 3 = 2 y - 4 = - 1 x = -1 y = 3 D (-1,3)

    (3)

    6y

    5xCD

    1

    2AB

    ABCD

    1

    2

    6y

    5x

    x 5 = 2 y - 6 = - 1 x = 7 y = 5 D (7,5)

    (4)

    7y

    1xCD

    1

    2AB

    ABCD

    1

    2

    7y

    1x

    x + 1 = 2 y + 7 = - 1 x = 1 y = - 8 D (1,-8)

  • - 24 - www.focus-physics.com

    4. 3,4A 5,1B C CD ABCD D

    (1) 2,1D (2) 3,4D

    (1)

    8

    5

    35

    41AB

    y2

    x1CD

    ABCD

    8

    5

    y2

    x1

    -1- x = -5 -2 - y = 8 x = 4 y = -10 C (4,-10)

    (2)

    8

    5

    35

    41AB

    y3

    x4CD

    ABCD

    8

    5

    y3

    x4

    4 - x = -5 3 - y = 8 x = 9 y = -5 C (9,-5)

  • - 25 - www.focus-physics.com

    5. A(3,2)

    5

    3AB B

    A )y,x(11

    B )y,x(22

    5

    3AB =

    12

    12

    yy

    xx =

    2y

    3x

    2

    2

    2

    x - 3 = - 3 2

    x = 0

    2y - 2 =5

    2y =7

    B (0,7)

    6. B(-4,5) 2AB2

    A

    A )y,x(11

    B )y,x(22

    2

    2AB =

    12

    12

    yy

    xx =

    1

    1

    y 5

    x4

    - 4 - 1

    x = 2 1

    x = - 6 5 -

    1y = - 2

    1y = 7

    A (-6,7)

    3

    x , y , z x

    y

    z

  • - 26 - www.focus-physics.com

    x

    y

    z

    (O) P(x, y,z) 1 1 1P(x , y ,z )

    2 2 2Q(x , y ,z ) 2 1

    2 1

    2 1

    x x

    PQ y y

    z z

    Z

    X

    Y

    O

    P x, y, z

    OP

    1.

    () 1 (1,3,7) (4,8,10) (4 1) i 8 3 j 10 7 k 3i 5 j 3k

    2 (3,5,4) (8,2,9) (8 3) i 2 5 j 9 4 k 5i 3 j 5k 3 ( 4,2,1) (3,5, 10) ( 3 4 ) i 5 2 j 10 1 k i 3 j 9k 4 (0,0,0) (4, 3,5) (4 0) i 3 0 j 5 0 k 4i 3 j 5k 5 (0,0,0) (4,4,4) (4 0) i 4 0 j 4 0 k 4i 4 j 4k

  • - 27 - www.focus-physics.com

    a c

    b d

    a c b d

    a d

    b e

    c f

    a d,b e c f

    a c a cb d b d

    a d a d

    b e b e

    c f c f

    0

    0

    0

    0

    0

    ab

    a

    b

    ab

    a

    b

    c

    a

    b

    c

    a

    b

    c

    a c a cb d b d

    a d a d

    b e b e

    c f c f

    a a

    b b

    a a

    b b

    c c

    2. 4u1

    , 2v7

    1. u v 2. u v 3. 3u 4. 2u 3v

    1. 4 2 6u v1 7 6

    2. 4 2 2u v1 7 8

    3. 4 3(4) 123u 31 3( 1) 3

    4. 4 72u 3v 2 31 2

    = 8 212 6

    = 294

  • - 28 - www.focus-physics.com

    3. 4

    u 1

    2

    3u

    34 3(4) 12

    u 3 1 3( 1) 3

    2 3(2) 6

    4.

    1 3u

    4

    2v7

    3 2

    4 7

    2 3u

    4

    6v8

    3 6

    4 8

    3 2u

    2 2

    1

    v2

    2 1

    2 2 2

    4. 1u

    4

    2v8

    1 2

    4 8

    5 1u

    2

    2v4

    1 2

    2 4

    6 8u

    4

    4v2

    8 4

    4 2

    7 1u 2

    1

    2

    v 4

    2

    1 2 1

    2 4 2

    8. 1u 2

    1

    4

    v 5

    6

    1 2 1

    4 5 6

    9. 1u 2

    4

    2

    v 4

    8

    1 2 4

    2 4 8

    10. 2u 3

    4

    4

    v 6

    8

    2 3 4

    4 6 8

    1. u v u kv k 2. u v

  • - 29 - www.focus-physics.com

    (unit vector )

    O

    y

    x

    2 2Q x , y

    1 1P x , ya

    b

    PQ

    z

    y

    x

    O

    1 1 1P x , y , z

    2 2 2Q x , y , z

    PQ

    1) ab

    2 2a b

    2) ab

    2 2

    a1

    ba b

  • - 30 - www.focus-physics.com

    3) a

    b

    c

    2 2 2a b c

    4) a

    b

    c

    2 2 2

    a1

    ba b c

    c

    5) PQ PQ

    1 i (

    0

    1

    0

    0

    1

    ) , j (

    1

    0

    0

    1

    0

    ) k (

    1

    0

    0

    )

    1

    u a i b j 2 2u a b

    1 u 3i 4 j 5 2 u 6i 8 j 10 3 u 5i 12 j 13 4 u 15i 8 j 17 5 u 5i 12 j 13 6 u i 2 j 4k 21 7 u 2 i 2 j 2k 2 3 8 u 4i 2 j 6k 56 9 u 3i 4 j 5k 50 10 u i j k 3

  • - 31 - www.focus-physics.com

    2. 1. u 6 i 8 j

    2 2

    u 6i 8 j 6i 8 j 6 i 8 j

    u 10 10 106 8

    2. u 3i 4 j

    2 2

    u 3i 4 j 3i 4 j 3i 4 j

    u 5 5 53 4

    3. u 5i 12 j

    2 2

    u 5i 12 j 5i 12 j 5i 12 j

    u 13 13 135 12

    4. u 7 i 24 j

    2 2

    u 24i 7 j 24 i 7 j 24 i 7 j

    u 25 25 2524 7

    5. 5 u 2 i 3 j

    2 2

    u 2i 3 j 2 i 3 j 2 i 3 j5 5 5 5

    u 13 13 132 3

    6.3 u 3i 4 j

    2 2

    u 3i 4 j 3i 4 j 3i 4 j3 3 3 3

    u 5 5 53 4

    7.10 u 8i 15 j

    2 2

    u 24i 7 j 24 i 7 j 24 i 7 j

    u 25 25 2524 7

    8. 7 u 7 i 24 j

    2 2

    u 24i 7 j 24 i 7 j 24 i 7 j7 7 7 7

    u 25 25 2524 7

    9. u 2i 6 j 3k

    2 2 2

    u 2i 6 j 3k 2i 6 j 3k 2i 6 j 3k

    u 7 7 7 72 6 3

    10. u i 2 j 4k

    2 2 2

    u i 2 j 4k i 2 j 4k i 2 j 4k

    u 21 21 21 211 2 4

  • - 32 - www.focus-physics.com

    11. u 2i 5 j 2k

    2 2 2

    u 2i 5 j 2k 2i 5 j 2k 2i 5 j 2k

    u 33 33 33 332 5 2

    12. 18 u i 4 j 8k

    2 2 2

    u i 4 j 8k i 4 j 8k18 18 18 2i 8 j 16k

    u 91 4 8

    (direction cosines ) a

    1

    2

    3

    a

    a a

    a

    a 0 X , Y , Z

    31 2 aa a, ,a a a

    z

    y

    x

    R

    S

    Q

    O

    1 2 3P a ,a ,a

    2

  • - 33 - www.focus-physics.com

    P(-1,2,3) Q(2,3,5)

    PQ =

    35

    23

    )1(2

    =

    8

    1

    3

    PQ = 74)8(13 222

    PQ 74

    8,

    74

    1,

    74

    3

    3.4 1 1u x i y j 2 2v x i y j u v 1 2 1 2u.v x x y y 1 1 1u x i y j z k 2 2 3v x i y j z k u v 1 2 1 2 1 2u.v x x y y z z u v u v 1. u 2 i 3 j 4 i j u v v u u v 2i 3 j . 4 i j = 2 4 3 1 = 38 = 5 v u 4i j . 2 i 3j = 4 2 1 3 = 38 = 5

    2 4

    u 1

    2

    2

    v 3

    4

    u v

    4 2

    u v 1 . 3 4 2 1 3 2 4 13

    2 4

  • - 34 - www.focus-physics.com

    1. u, v w a 1) u v v u ( ) 2) u v w u v u w ( ) 3) a u v au v u av 4) 0 u 0 5) 2u u u 6) i i j j k k 1 i j i k j k 0 2. u v 0 180 u v u v cos () 3. u v u v u v 0

    v

    u

    v

    u

    v

    u

    u

    v 180u v

    u

    v

    u

    v

    u v u v cos vu

  • - 35 - www.focus-physics.com

    21 u.u u 2 u.v u v cos 2 2 23 u v u 2u v v 2 2 24 u v u 2u v v 2 2 2 25 u v u v 2 u 2 v 2 26 u v u v 4u v 2 27 u v . u v u v 2 2 2 28 u v w u v w 2u v 2v w 2w u 2 2 2 29 u v w u v w 2u v 2v w 2w u 2 2 2 210 u v w u v w 2u v 2v w 2w u 11 u v . w s u w u s v w v s 2 2 22 212 au bv a u 2abu v b v 3 1 3

    u4

    4v3

    u v 0

    2 3u

    4

    6v8

    u v 0

    3 2u

    2

    1v1

    u v 0

    4. 1u4

    5v8

    u v 0

    5 1u2

    2v1

    u v 0

    6 8u

    4

    4v2

    u v 0

    7 1u 2

    1

    2

    v 4

    2

    u v 0

    8. 1u 2

    1

    4

    v 5

    6

    u v 0

  • - 36 - www.focus-physics.com

    9. 1u 2

    1

    0

    v 4

    8

    u v 0

    10. 2u 3

    4

    4

    v 6

    8

    u v 0

    4 . u v u 5 , v 8 vu

    vu u v 1. 0 2. 30 ( 1 ) 0 2 2 2u v u v 2 u v cos 2 22u v 5 8 2 5 8 cos0 2u v 25 64 2 5 8 1 2u v 169 u v 169 13

    2 2 2u v u v 2 u v cos 2 22u v 5 8 2 5 8 cos0 2u v 25 64 2 5 8 1 2u v 9

    u v 9 3 ( 2 ) 30 2 2 2u v u v 2 u v cos 2 22u v 5 8 2 5 8 cos30

    2 3u v 25 64 2 5 82

    2u v 89 40 3

    u v 89 40 3 2 2 2u v u v 2 u v cos 2 22u v 5 8 2 5 8 cos30

    2 3u v 25 64 2 5 82

    2u v 89 40 3

    u v 89 40 3

  • - 37 - www.focus-physics.com

    5 u v 5 2 | u v | 26 u v 1. 3 2. 6 3. 8 4. 12 | u v | 5 2 | u v | 26

    2 2 2 2 2 2| u v | | u v | (| u | | v | 2u v) (| u | | v | 2u v) 2 2(5 2) ( 26) 4u v

    50 26 4u v 24 4u v

    24u v 64

    2.

    6 u v 60 | u v | 37, | u v | 13 | u | | v | 1. 5 2. 7 3. 37 4. 50 2 2 2| u v | | u | 2u v | v | 37 ..(1)

    2 2 2| u v | | u | 2u v | v | 13 ..(2) (1)+(2) 2 22 | u | 2 | v | 50 2 2| u | | v | 25 ..(3) (1)-(2) 4u v 24

    u v 6 | u || v | cos60 6 (u v | u || v |)cos

    1| u || v | 62

    4 ; 2 | u || v | 24 (4) (3)+(4) 2 2| u | 2 | u | | v | | v | 49 2(| u | | v |) 49

    | u | | v | 7 2. 7 u v u v

    u.v u v cos

    -1

    u v 2 2 4cos

    4 1 4 1 4 4u v

    8 8cos cos

    9 9

    u 2 i j 2k , v i 2 j 2k

  • - 38 - www.focus-physics.com

    8 u i 3 j, v 2i j (u v) (u v) cos

    1. 5

    1 2 . 5

    2 3. 5

    1 4. 5

    2

    u i 3 j, v 2i j

    u v 3i 4 j, u v i 2 j 2 2| u v | 3 4 25 5 2 2| u v | ( 1) 2 5 (u v) (u v) 3( 1) 4(2) 3 8 5 (u v) (u v) | u v || u v | cos

    5 5 5 cos 5 1cos

    5 5 5 1.

    9. u v u v u v u 2v u 2v 2u v | u | 2 cos

    1. 10

    1 2. 6

    1 3. 4

    1 4. 2

    1

    u v u 2v (u v) (u 2v) 0

    2 2| u | u v 2 | v | 0 (1) u 2v 2u v (u 2v) (2u v) 0

    2 22 | u | 3u v 2 | v | 0 (2) (2)-(1) 2| u | 4u v 0 2( 2) 4u v 0

    1u v2

    .(3)

    (1) 5| v |2

    (3) 10

    1cos 1.

  • - 39 - www.focus-physics.com

    10. u ai bj a 0 b 0 u (5i 2 j) 14 u

    i 3cos5

    a b

    1. 7 2. 14 3. 18 4. 21 u (5i 2 j) (ai bj) (5i 2 j) 5a 5b 14

    5a 14b2

    u i | u || i | cos

    2 2 29a (a b )25

    3a b4

    3 (5a 14) 426,4 2 23

    56b 8,23

    a b 6 8 14 2 11. u v 6 u v 2 u v

    2 2u v u v 4u v

    2 2

    6 2 4u v

    4 4u v u v 1 12 A,B,C O OA 3i 2 j

    OB 2i 5 j 2AC AB3

    2| OC |

    1. 9

    113 2. 9

    98 3. 9

    193 4. 9

    159

    AB OB OA (2i 5 j) (3i 2 j) i 7 j

    2 2AC AC ( i 7 j)3 3

    OC OA AC

    2 7 8(3i 2 j) ( i 7 j) i j3 3 3

    2 49 64 113| OC |9 9 9

    1.

  • - 40 - www.focus-physics.com

    13. u 4i 3 j,| v | | u | | u v | 8 u.v 1. 6 2. 7 3. 12 4. 14

    u 4i 3 j 2 2| v | | u | 4 3 5 2 2 2u v u 2u v v 2 2 28 5 2u v 5

    64 25 25u v 72

    2.

    14. u,v,w u 5v 2w 0 u 3i 4 j u v u w | w | cos 1. 2 2. 2.5 3. 3 4. 3.5

    u 3i 4 j 2 2| u | 3 4 5 u v u v 0 u 5v 2w 0 ..(1)

    u 5v 2w 2 2| u 5v | | 2w | 2 225 | v | 4 | w | 25 (2) (1) 5v 2w u 2 2 225 | v | 4 | w | 4w u | u | ....(3)

    (2)=(3) 50| w | cos 2.520

    2.

  • - 41 - www.focus-physics.com

    2 3 1u , v , w3 0 4

    1. 2 3 5u v3 0 3

    2. 2 1 2 2 0u 2w 23 4 3 8 5

    3 . u v 2 3 3 0 6

    4. 1 1 6

    u v w 2 3 3 0 64 4 24

    5. u v w

    6. 22u 2 3 13

    7 . 2 2v 3 0 3

    8. Cos u v u v u v cos

    u v 6 2cos3 13 13u v

    9 . 2 3 1 2 4

    u v w . 8 12 203 0 4 3 4

    10. 2 1 2 3u v u w . 2 12 6 0 203 4 3 0

    11. 1 u

    2

    3u 2 i 3 j

    13 13 13u

    12. 3 v

    3

    0v3 3 3i

    3v

  • - 42 - www.focus-physics.com

    (Projection Vectors)

    y

    x

    v

    u

    O

    A

    OA (Projection Vectors) v u

    2

    u.vOA u

    u

    1. O , OA 3i 4 j,OB 5i 2 j A OB D OD

    1. 7 5i 2 j29

    2. 7 5 i 2 j29

    3. 8 5i 2 j29

    4. 8 5 i 2 j29

    A

    B

    D

    O

    OA 3i 4 j, OB 5i 2 j 22OB 5 2 29

    OB.OA 5 3 2 4 7

    2

    OB.OAOD OB

    OB

  • - 43 - www.focus-physics.com

    2

    7OD 5i 2 j

    29

    7OD 5i 2 j29

    2. OA 3i 4 j, OB 12 i 5 j BC OA C OC

    1. 5 3i 4 j16

    2. 16 3i 4 j5

    3. 16 3i 4 j25

    4. 25 3i 4 j16

    A

    B

    C

    O

    OB 12i 5 j OA 3i 4 j 22OA 3 4 5

    OB.OA 12 3 5 4 16

    2

    OB.OAOC OA

    OA

    2

    16OC 3i 4 j

    5

    16OC 3i 4 j25

  • - 44 - www.focus-physics.com

    3 . OA 3i 4 j, OB 12 i j AC OB C OC

    1. 8 12 i j29

    2. 29 12 i j8

    3. 40 12 i j145

    4. 140 12 i j45

    y

    x

    A

    O

    C

    B

    OA 3i 4 j

    OB 12 i j 2 2OB 12 1 145 OB.OA 12 3 1 4 40

    2

    OB.OAOC OB

    OB

    240

    OC 12i j

    145

    OC 40 12 i j145

  • - 45 - www.focus-physics.com

    C AB

    O

    m n

    vu

    w

    nu mvwm n

    2 2B x , y 1 1A x , y

    m n

    C x, y

    2 1mx nxx

    m n

    2 1my nyym n

    1. ABC D AB AB AD : DB 3: 2 CA 3i 2 j, CB 2 i 3 j CD

    1. 95

    2. 115

    3. 135

    4. 145

    C

    AB

    D

    3 2

    CA 3i 2 j CB 2 i 3 j

    3CB 2CACD

    5

    3 2 i 3 j 2 3i 2 j

    5

    6i 9 j 6 i 4 j

    5

    12

    i j5

    2

    212 13CD 15 5

  • - 46 - www.focus-physics.com

    2. A,B,C O OA 3i 2 j

    OB 2 i 5 j 2AC AB3

    2

    OC

    1. 1139

    2. 989

    3. 1939

    4. 1539

    CAB

    O

    2 1

    OA 3i 2 j OB 2 i 5 j

    2OB 1OAOC

    2 1

    2 2 i 5 j 1 3i 2 j

    2 1

    2 12 i 5 j 3i 2 j

    3 3

    7 8

    i j3 3

    2 2

    2 7 8 113OC

    3 3 9

    3. A 3, 2 ,B 9,4 O 0,0 AB 3 C D OC OD

    C

    O 0,0

    3OA

    2

    9OB

    4

    D A 3, 2 B 9,41 1 1

    3OA

    2

    9OB4

  • - 47 - www.focus-physics.com

    3 9 52OA 1OB 2 1OC

    2 4 02 1 3 3

    3 9 71OA 2OB 1 2OD

    2 4 22 1 3 3

    OC OD 5 7 0 2 35

    4 . A 1,1 ,B 4,10 ,C 7,9 D AB AD 2

    3AB

    CA DC cos

    1. 25

    2. 210

    3. 25

    4. 210

    D

    2 1

    A 1,1

    C 7,9

    B 4,10

    6CA

    8

    3CB

    1

    6CA

    8

    3CB1

    1CA 2CBCD3

    6 31 2

    48 1CD

    23

    4DC

    2

    CA DC cos

    6CA8

    2 2

    CA 6 8 10

    4DC

    2

    2 2DC 4 2 20

    CA.DC 6 4 8 2 40

  • - 48 - www.focus-physics.com

    CA.DC CA . DC cos

    CA.DC CA . DC cos

    40 10 20 cos 2

    cos5

    5 . A B 10,0 2,4

    AB C AC 1

    3CB

    O COB

    1. 210

    2. 110

    3. 110

    4. 210

    C AB

    O

    3 1

    OA 10 i OB 2 i 4 j

    1OB 3OAOC

    4

    1 2 i 4 j 3 10 i

    4

    7 i j

    7 2 1 4OC OB 1

    cos50 20 10OC OB

  • - 49 - www.focus-physics.com

    6. ABC D BC BD : BC 1:3

    . 3AD 2AB BC . 21

    AD BC BC6

    1. . . 2. . . 3. . . 4. . .

    A

    BC2 1

    D . 2AB 1ACAD

    3

    3AD 2AB 1AC .

    . . 2 1AD BC AB AC BC3 3

    2 1AB BC AC BC3 3

    A

    B

    DC

    2 1

    120

    60

    aa

    2 1AD BC AB BC AC BC

    3 3

    2 1AD BC AB BC cos AC BC cos3 3

  • - 50 - www.focus-physics.com

    a

    22 1 1AD BC a a cos120 a a cos 60 a3 3 6

    . 3. 7 . A,B, C D BC

    BD : DC 2 :1 2 2 2

    AD a AB b AC c AB AC a,b,c

    AB AC 0 2 2 2a b c

    1. 3181

    2. 3281

    3. 1027

    4. 1127

    A

    B C2 1

    D 1AB 2ACAD

    3

    1 2AD AB AC3 3

    1 2

    AD AB AC3 3

    2 2 21 4 4

    AD AB AB AC AC9 9 9

    2 2 2

    2 2 2 1 4 4 11a b c9 9 9 27

  • - 51 - www.focus-physics.com

    3.5

    1

    2

    3

    a

    u a

    a

    1

    2

    3

    b

    v b

    b

    2 3 3 2

    3 1 1 3

    1 2 2 1

    a b a b

    a b a b

    a b a b

    2 3 1 3 1 22 3 1 3 1 2

    a a a a a ai j k

    b b b b b b

    u v

    1 2 31 2 3

    i j k

    u v a a a

    b b b

    1. u,v,w k 1) u v v u 2) u v w u w v w 3) u v w u v u w 4) u kv k u v 5) ku v k u v 6) u u 0 7) i j k , j k i , k i j 2. u,v,w u v w u v w 3. u 0 v 0 u v u v sin u v 0 180 4. u v u v u v

  • - 52 - www.focus-physics.com

    1. 4

    u 2

    4

    6

    v 3

    0

    u v

    u v = i j k

    4 2 4

    6 3 0

    = 2 4 4 4 4 2i j k3 0 6 0 6 3

    = ( 2 0 3 4 ) i ( 4 0 4 6 ) j ( 4 3 2 6 k = 12 i 24 j 0k = 12 i 24 j

    v

    u

    v sin

    v

    u

    v sin

    u v u v sin 1 1u v u v sin2 2

    v r

    u

    h r

    v u , v r h u v r u v r h u cos v r

  • - 53 - www.focus-physics.com

    = v r u cos = u v r cos u v r

    u , v w )wv(u = 0

    1 2 3 1 2

    1 2 3 1 2

    1 2 3 1 2

    u u u u u

    (u v) r v v v v v

    w w w w w

    1. ABCD AB 2 i j k AD i j 2k AB AD

    i j k

    AB AD 2 1 1

    1 1 2

    1 1 2 1 2 1i j k1 2 1 2 1 1

    = 1 2 1 1 i 2 2 1 1 j 2 1 1 1 k = i 3 j k 2 2 2AB AD 1 3 1 11

    2. u i 2 j 3k , v 2 i 3 j , r j 2k u v r

    i j k

    v r 2 3 0

    0 1 2

  • - 54 - www.focus-physics.com

    = 3 0 2 0 2 3i j k1 2 0 2 0 1

    = 6 i 4 j 2k u v r i 2 j 3k 6 i 4 j 2k

    = 1 6 2 4 3 2 = 686 = 20 = 20 3 u i 2 j , v 3i j 5k , r 2 i 7k

    1 2 0 1 2

    u v r 3 1 5 3 1

    2 0 7 2 0

    7 20 0 0 0 42 55 5555

    4. 3 A, B C A i 2j k , B 21 3k C 7j 4k

    1 2 1 1 2

    (A B) C 2 0 3 2 0

    0 7 4 0 7

    (A B) C -23 23