25 Баллов!6sin^2х + 5sin( п\2-х)-2=0

Question

25 Баллов!
6sin^2х + 5sin( п\2-х)-2=0

Answer 1

6 - 6cos^2(x) + 5cos(x) - 2 = 0

6cos^2(x) - 5cos(x) - 4 = 0

D = 25 + 96 = 121

[cos(x)]1 = (5 - 11) / 12 = -1/2

[cos(x)]2 = (5 + 11) / 12 > 1 - не удовл. E(cos(x))

x = +-(pi - pi/3) + 2pik = +-2pi/3 + 2pik, k E Z