Тригонометрические уравнения

cos2x+sin²x = 3/4, [π; 2,5π]

sin(π/2+x) = sin2x, [–π; π/2]

cos2x–5√2cosx–5 = 0, [–3π; –3π/2]

Решить уравнения:

1) cos²3x–sin²3x = 0
2) sinxcosx = √3/4
3) 5sin²x+sinx–6 = 0
4) 1–cos2x = 2sinx
5) 5sin²x+6cosx–6 = 0