Đáp án:
Giải thích các bước giải: a,200s 2 x+cos(π/2 - x )+1=0
(=) 2 (1-sin2 x) + sinx + 1 =0
(=) - 2sin 2 x + sin x + 3 =0
(=) sin x = 3/2 (∨On·)
[ sin x = -1 =>x=-π/2+h2I(h ∈ 7)π
(=) 4cos3x - 2cosx=√3(2 cos2x-1)
(=) 2 cosx(2cosx2-1) - √(2cosx2-1) = 0
(=) (2 cosx-√3)(2cosx-1) =0
(=) cosx=√√3/2 x=±π/6 + h2π
cosx = 1/√2 (=) x = ±π/4 + h2π (h∈z)
cosx = - 1/√2 x = ± 3π/4 + h2π
