Question

Помогите решить!.........................................................................................................

Answer 1

$cos x sqrt{4-x^2}<0\ left { {{sqrt{4-x^2}>0} atop {cos x<0}} right\ left { {-2< x < 2}atop{frac{pi}{2}+2 pi n < x <frac{3pi}{2}+2pi n$

$(-2; -frac{pi}{2})cup (frac{pi}{2}; 2)$