Phương trình bậc hai theo 1 hàm số lượng giác: sin(2x + 5π/2) - 3cos(x - π/2) = 1 + 2sinx; 5cosx - 2sinx/2 + 7 = 0

1) sin(2x+5π/2) - 3cos(x-π/2) = 1 + 2sinx
2) 5cosx - 2sinx/2 + 7 = 0
3) (sin2x + √3 × cos2x)^2 = cos(2x - π/6)
4) √3/sin^2x = 4cotx
5) cos2x - 3cosx = 4cos^2x/2
6) tanx + tan(x + π/4) = 2
7) 2tan^2x + 3 = 3/cosx
8) tan^2 2x + cot^2 2x = 2
9) sin^2 2x - 3/2sin^2x = sin^2π/6
10) 1 - 2sin^2x × cosx - 2cos^3x =0
11) sin2x + tand - 2 = 0
12) 2cosx/3 - sinx/2 = 2