, , . , B = {, , } . O . R = { O,, , } . . O:
= , = ,
= , =.
l 1 = OA, l 2 = OB, l 3 = OC. , , D . A 1, B 1, C 1 , l 1, l 2, l 3, D 1 .
= , = , = , = .
=, = + . = + . , = + + . ||, ||, ||, x 1, x 2, x 3, = x 1, = x 2, = x 3 Þ
= x 1 + x 2 + x 3 . (5)
B. x 1, x 2, x 3 . D R. (x 1, x 2, x 3) B, D (x 1, x 2, x 3) R. { O, A, B, C }.
- D . , -. O , l 1, l 2, l 3, , , , , . { O, A, B, C }, .
, D - Þ . . ,
= y 1 + y 2 + y 3, (5 ')
, , y 3 ≠ x 3 . (5 ') (5):
= (x 1 y 1) + (x 2 y 2) + (x 3 y 3), Þ
= +.
, . , , , . . , y 3 = x 3 . , y 2 = x 2, y 1 = x 1.
, , , . , , .
, , , B R . , , ,, , . i, j, k ; x, y, z; Ox, Oy, Oz; OE 1, OE 2, OE 3.
i, j, k .
, , .
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a =Ð( i, ), b =Ð(j, ), g =Ð(j, ). cos a, cos b, cos g .
: cos2a + cos2b + cos2g = 1.
1¢. ( ).
, , ( (a 1, a 2, a 3)½½ (b 1, b 2, b 3) Û = =).
. || Û $l: = l Û a 1= l b 1, a 2 = l b 2, a 3 = l b 3 Û Û == = l.