у больше или равно х -2.5 проходит через точки (5;2.5) и ( -5;7,5)
1. (1 - cos^2t / 1-sin^2t) + tgt*ctgt = 1 / cos^2t
sin^2t / cos^2t + 1 = (sin^2t + cos^2t) / cos^2t = 1 / cos^2t
1/cos^2t = 1/cos^2t
2. sint = -15/17
cos^2t = 1 - sin^2t = 1 - 225/289 = 64/289
cost = -8/17
tgt = sint/cost
tgt = 15*17/17*8 = 15/8
ctgt = 1/tgt = 8/15
5(х-3)-2(х-7)=7-7(2х+6)
5х-15-2х+14=7-14х-42
5х-2х+14х=7-42+15-14
17х=-34 |:17
х=-2
3(5-4а)-(12а-7)=15-12а-12а+7=22-24а
Если а=0,5, то 22-24а=22-24*0,5=22-12=10
11x^2 + 5 = x^2 + 3
10x^2 + 2 = 0
10x^2 = - 2
x^2 = - 1/5
нет реш