4cos^2 2x – 1 + 2cos^2 2x + 4sin2x = 0
4cos^2 2x + 4sin2x – 1 = 0
4 (1 - sin^2 2x) + 4sin2x – 1 = 0
4 – 4sin^2 2x + 4sin2x – 1 = 0
- 4sin^2 2x + 4sin2x + 3 = 0
4sin^2 2x -4sin2x – 3 = 0
sin2x = t
4t^2 -4t – 3 = 0
t_1,2 = (4±8)/8
t_1= 1,5
t_2 = - 1/2
sin2x = - ½
2x = ( - 1) ^(n+1) arcsin (1/2) + pi n
2x= ( - 1) ^(n+1)* pi/6 + pi n
x = ( - 1) ^(n+1)* pi/12 + (pi)/2 n
