Given y = 3cosx + 1 / SiNx + 2

Given y = 3cosx + 1 / SiNx + 2

y=(3cosx+1)/(sinx+2)
ysinx+2y=3cosx+1
ysinx-3cosx=1-2y
√(y^2+9)sin(x+φ)=1-2y
Then - 1 ≤ (1-2y) / √ (y ^ 2 + 9) ≤ 1
The solution of inequality is y ∈ [- 2 / 3,2]