2.2. , , () .
, : (.2.2).
R 1-2, Oab 1 2:
(P 1, P 2) ~ R 1-2 = 1+ 2.
R 1-2 3, b bc = 3:
( 1, 2, 3) ~ (R 1-2, 3) ~ R 1-3 = 1+ 2 + 3.
, :
(P 1, P 2,..., P n) ~ (R 1-(n -1) , P n) ~ (R 1- n ) ~ R = P i,
Oabcd.
, , .
, .
:
1. , , - .
2. , , , .
, , .
. Ox , .
Px X. :
Px = X =½ ½× cos (, i) = P × cosa = ( × i),
i - Ox, a - (.2.3). :
ì > 0, 0 £ a< p/2;
Px í = 0, a = p/2;
î < 0, p/2 < a £ p.
Oy.
- , , . , , 2.2:
= Px × i + Py × j = X× i + Y × j.
. - X,Y,Z - A (x, y, z), .
|
|
, X,Y,Z. X , X >0 , - X <0.
, , . , 2.2, :
= X× i + Y × j + Z× k. (2.1)
, , , .
:
____________ = Ö X 2 + Y 2+ Z 2; cos (, i) = X / ; cos (, j) = Y / ; cos (, k) = Z / . |
(2.2)