Question

$2sin^{2} x+5sin(1.5 pi -x)=2$

Answer 1

2-2cos²x-5cosx-2=0
2cos²x+5cosx=0
cosx(2cosx+5)=0
cosx=0⇒x=π/2+πn
2cosx=-5⇒cosx=-2,5∉[-1;1]