Question

cos^2 - sin 2x= 0   ///////////////////

Answer 1

COS^2(X)-SIN(2X)=0

cos^2(x)-2sin(x)cos(x)=0

cos(x)[cos(x)-2sin(x)]=0

1) cos(x)=0

    x=(pi/2)+pi*n 

2) cos(x)-2sin(x)=0

    cos(x)=2sin(x)

    2sin(x)/cos(x)=cos(x)/cos(x)

    2tg(x)=1

    tg(x)=1/2

    x=arctg(1/2)+pi*n