, .
:
l 1: A 1 x + B 1 y + C 1 = 0 ,
l 2: A 2 x + B 2 y + C 2 = 0 .
, (A 1, B 1) (A 2, B 2) l 1 l 2.
2. 1. l 1½½ l 2 l 1¹ l 2 Û = ¹.
2. l 1= l 2 Û = =.
3. l 1^ l 2 Û A 1 A 2 + B 1 B 2 = 0.
4. l 1 l 2
cos a = =. (16)
. 1, 2. , l 1½½ l 2 Û ½½,
= = l. (*)
, Û M o(x o, y o), . .
A 1 x o + B 1 y o + C 1 = 0,
A 2 x o + B 2 y o + C 2 = 0.
, l:
(A 1 l A 2) x o + (B 1 l B 2) y o + C 1 l C 2 = 0.
(*) Þ C 1 l C 2 = 0 Û C 1/ C 2 = l. (**) (*) (**), .
, 2, l 1 l 2 , .., l, . .
3, 4. , , . , a 0 £ a £ p/2.
b =Ð(,). 0 £ b £ p.
, b , .
1 : 0 £ b £ p/2. a = b Þ
cos a = cos b =.
2 : p/2 < b £ p. a = p b cos b < 0 Þ
cos a = cos (p b) = cos b =
=½ cos b½ = .
: . (16) , . , (16) , l 1^ l 2 Û = 0 Û A 1 A 2 + B 1 B 2 = 0.
1. . , , .
2. , .
2.
l 1: y = k 1 x + q 1, l 2: y = k 2 x + q 2.
tg q =.
. k 1= tg a1, k 2 = tg a2 , q1 q2 , (. ). q1= b a, , q1£ p/2, l 1 l 2. tg q1³ 0.
|
|
:
tg q1= tg(b a) = =.
q1> p/2, q2 = p q1.
tg q2 = tg(p q1) = tg q1=½tg q1½ =.
.
, , , l 1 l 2, ( ). p £ q £ p.