, R = { O, , , } R ¢ = { O, , , } , . , (x 1, x 2, x 3) , (, x 2¢, x 3¢) . (x 1, x 2, x 3) , (, x 2¢, x 3¢) .
. B ¢ = { , , } B = { , , } :
= 11 + 21 + 31,
= 12 + 22 + 32, (20)
= 13 + 23 + 33.
, :
11 12 13
= 21 22 23
31 32 33 .
. :
= x 1 + x 2 + x 3
= x 1¢ + x 2¢ + x 3¢.
(20):
= x 1¢ ( 11 + 21 + 31) + x 2¢ ( 12 + 22 + 32 ) + x 3¢ ( 13 + 23 + 33 ).
:
= ( 11 x 1¢ + 12 x 2¢ + 13 x 3¢) + ( 21+ 22 x 2¢ + 23 x 3¢) + ( 31+ 32 x 2¢ + 33 x 3¢).
(*), ,
x 1= 11 x 1¢ + 12 x 2¢ + 13 x 3¢,
x 2 = 21+ 22 x 2¢ + 23 x 3¢, (21)
x 3 = 31+ 32 x 2¢ + 33 x 3¢.
,
x 1 x 1¢
X = x 2 X ¢= x 2¢
x 3, x 3¢,
(21) :
X = CX ¢ (21¢)
Þ X ¢= C 1 X,(22)
.. , , , (21), C 1, . (21) x 1¢, x 2¢, x 3¢ .
, . . .
-, (21¢) (22). , , (17) (17¢) . O ¢(a, b, c) c
x 1= x 1¢ + a, x 1¢ = x 1 a,
x 2 = x 2¢ + b, (22) x 2¢ = x 2 b, (22¢)
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x 3 = x 3¢ + c. x 3¢ = x 3 c.
.
.
1. ABCD , O , M, N, P, Q AB, BC, CD, DA . = = . {, }.
. = + ; =,
= + = +. = (+) + = + . ,.
:.
2. (17, 0) (1, 1) . l, = +l | | = 25 ( , ). , .
. = +l· (17 l, 0 + l). 25. l:
(17 l)2 + l2 = 625,
2l2 34l + 289 = 625 Û 2l2 34l 336 = 0, Û
Û l2 17l 168 = 0.
, l1 = 7;l2= 24. , l1= 7. (24, 7). , ||, , .. 25:.
: l1= 7,.
3. (2, 2) . , : a) a = 120o, ) b = 90. =. A, Ox.
. (x ¢, y ¢), (x, y) a, :
x ¢= x ·cos a y ·sin a,
y ¢= x ·sin a + y ·cos a.
( , !)
) cos a = , sin a =.
x ¢= (2) + 2· = 2,
y ¢= 2· 2·() = 2.
) sin 90=1; cos 90= 0 (2,2).
(x, y), (r, φ) :
r =,
cos j =, sin j =.
-. (2,2). r = 4; cos j = ; sin j = . j =. (4, ).
: ) (2,2); ) (2,2); (4, ).
4. A (3,-2), B (8, 5) ABCD. .
. (5, 7). 90, 90. , .
, , (7, 5), (7,5). , D A : D (- 4, 3). , = C (1, 10). .
: C (1, 10), D ( 4, 3), C ¢(15, 0), D ¢(10,8).
5. A (1, 2), B (7, 6), C (11,3), D (8, 1). , ABCD . , cosÐ DAB.
. (6,8), (4, 3), (3, 4), (7,1). , :
= , .
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= , .
, , . , AB CD. :
½½ = = 10,
½½= 5; ½½=5; ½½= 5.
a =Ð BAD.
cos a = = =,
Ð BAD = 45o. , : cos a,
sin a = =.
T h =½½ sin a = 5. : S =(AB + CD) h =.
: ½½ = 10, ½½= 5, cos a =, SABCD =.
6. ½½= 10, ½½ = 3, a =Ð(, ) = 30o. , = 3 = 2 + 5, . , .
. , . , : SΔ= ½ ´ ½.
½ ´ ½=½( 3 )´(2 + 5 )½=½ ´ + 5 ´ 3´ 15 ´ ½=
=½ + 5 ´ + 3 ´ +15½= 8½ ´ ½= 8½½½½sin a =
= 8103 = 120.
SΔ= ½ ´ ½= 60 .
AD D ABC, = (+). ,
, , = ( + ) = +.
. : 2 = ½½2.
½½2= = ( + )(+ ) = 2 + 3 + 2=
= ½½2+ 3½½½½ cos a +½½2 =
= 100 + 3103 + 9 = 234 + 45.
, ½½ =.
: S Δ= 60, .
, 2 ´; 2 . , ´ = ´ .
7. , (10, 11, 2) (10,10, 5) , , , .
. , , . :
= 1011 + 11(10) + 2 5 = 0 Þ ^ ,
| | = = 15,
| | = = 15.
, , .
´ . , :
½ ´½=½½ ½½ × sinÐ( , ) = 1515 sin 90o= 225.
15. , = ´ .
´ = = 75 i 30 j 210 k, (5, 2,14).
, = .
: (5, 2,14), (5, 2,14).
8. SABC: A (4, 0, 1), B (5,1, 1), C (4, 7,5), S (7, 5, 2). , ABC ( ). Ð BAC. , . .
. , :
(1,1, 0), (0, 7, 6), (3, 5, 1).
, . 1/6 : V = ½½.
:
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=
, ´, : =(´) . , . .
´ = = i j + k = 6 i + 6 j + 7 k.
S Δ ABC = ½´½= = .
(´) = 6×3 + 6×5 + 7×1 = 55. V = ½(´)½= .
C , V = SΔ ABC h . h = = = 5.
´ . = ´ ; (6, 6, 7). Ð BAC , 5.
xyz.
: V = , S Δ ABC = , h = 5, (6, 6, 7).
9. ABC, A , : B (6, ), C (4, ). BC. .
. , B C . ,
Ð BAC = j1 j2 = = ,
AB = 6, AC = 4.
SΔ ABC = AB × AC ×sinÐ BAC = ×6×4×sin = 12× = 6.
BC 2= AB 2 + AC 2 2× AB × AC ×cosÐ BAC = 36 + 16 2×6×4×( ) = 76.
: S Δ ABC = 6, BC = = 2.
10. O ¢(2,1) a = arccos .
) , . A, : A (6, 2).
) , . B, : B (5, 5).
. )
x ¢= (x a) × cos a + (y b) × sin a,
y ¢= (x a) × sin a + (y b) × cos a,
(a, b) O ¢, a . cos a sin a :
x ¢= (x 2) + (y + 1),
y ¢= (x 2) + (y + 1).
A (6, 2) Oxy x ¢= 5, y ¢= 0. A (5, 0) O ¢ x ¢ y ¢.
)
x = x ¢ × cos a y ¢ × sin a + a,
y = x ¢ × sin a + y ¢ × cos a + b.
x = x ¢ y ¢ + 2,
y = x ¢ + y ¢ 1.
B (5, 5) O ¢ x ¢ y ¢ B (3, 6) Oxy.
: A (5, 0) O ¢ x ¢ y ¢, B (3, 6) Oxy .