A)2sin^2 x - 1=0 b)6sin^2 x + sin x = 2 c)cos^2*2x - 1 - cos x = корень из 3/2 - sin^2*2x

a)
2sin^2 x - 1=0
2sin^2 x  = 1
sin^2x = 1/2
sinx = ± √2/2

sinx = √2/2
x = pi/4 + 2pik
x = 3pi/4 + 2pik

sinx = - √2/2
x = - pi/4 +2pik
x = 5pi/4 + 2pik


b)
6sin^2 x + sin x -  2 = 0
(3sinx + 2)( 2sinx - 1) = 0

sinx = - 2/3 ===> x = (-1)^(k+1)*arcsin(2/3) + pik, k ∈ Z
sinx = 1/2 ==> x = (-1)^k * pi/6 + pik, k ∈ Z