. ,
Ax + By + C = 0, (14)
, A 2+ B 2 = 1. , (A, B) .
(14) , , :
x + y + = 0.
2+ 2= 1.
3. l (14) . M (x 1, y 1)
h =½ Ax 1+ By 1+ C ½. (17)
. (14),
h = . (17¢)
. (A, B) l. , ½½ = 1. M o(x o, y o) . MN
l . a =Ð( , ), b =Ð MM o N .
1 . M l.
h =½ MN ½=½ MM o½sin b =½½sin( a) =
=½½cos a½½=
( ½½, ). , (x 1 x o, y 1 y o) Þ
h = A (x 1 x o) + B (y 1 y o) = Ax 1+ By 1+ C (Ax o+ By o+ C)
( C ). M oÎ l, ,
h = Ax 1+ By 1+ C.
2 . M l. b = a p/2 Þ sin b = cos a
h = = Ax 1 By 1 C.
h , h ³ 0.
, Ax 1+ By 1+ C < 0 ( , .. M Ï l).
h =½ Ax 1+ By 1+ C ½.
.
, Ax 1+ By 1+ C , M. M 1, M 2 , l (Û M 1 M 2 l ).
5. .
l , OP . ON l. p =½ ON ½ , a OP ON. M (r, j) .
D OMN
p = r cos(a j) p = r cos(j a). (18)
, .
, M (r, j) (18), D OMN Þ M Î l.
, (18) .
, Ox OP. (18) :
r cos j cos a + r sin j sin a p = 0.
r cos j = x, r sin j = y Þ
x cos a + y sin a p = 0. (19)
|
|
. : p , , a Ox . cos2a + sin2a = =1, , .
. : l 1: p 1 = r cos(a1 j), l 2: p 2 = r cos(a2 j). , . , l 1 l 2, .
.
:
l 1: A 1 x + B 1 y + C 1 = 0,
l 2: A 2 x + B 2 y + C 2 = 0.
,
(l A 1+m A 2) x + (l B 1+m B 2) y + l C 1+ m C 2 = 0, (20)
l m . . , l = 1, m = 0 l 1, l = 0, m = 1 l 2. , l 1 l 2 .
4. 1. l 1 l 2 M o, , , M o.
2. l 1½½ l 2, .
. 1. (20)
l(A 1 x + B 1 y + C 1) + m(A 2 x + B 2 y + C 2) = 0. (20¢)
M o(x o, y o) = l 1I l 2. . (20¢):
l(A 1 x o+ B 1 y o+ C 1) + m(A 2 x o+ B 2 y o+ C 2) = 0.
, l m. , (20) M o.
, , M o. M (x 1, y 1) , M o. (20¢)
X = A 1 x 1+ B 1 y 1+ C 1, Y = A 2 x 1+ B 2 y 1+ C 2.
l X + m Y = 0 (*)
l m. (lo, mo). l=lo m=mo (20) , M.
2. l 1½½ l 2.
= = k.
l (20). l 2:
= Û l + m = l + m Û l k + m = l k + m,
.. . l ½½ l 2.
, l 1 l 2. M (x 1, y 1) , l 1, l 2. (20¢) (*) l m, X Y . l m , (*) (20) , M.
M o, M o , . , .