2cos4x-4sin(pi/2+2x)+3=0

Question

2cos4x-4sin(pi/2+2x)+3=0

Answer 1

4cos²2x-2-4cos2x+3=0
cos2x=a
4a²-4a+1=0
(2a-1)²=0
2a=1
a=1/2⇒cos2x=1/2⇒2x=+-π/3+2πn,n∈Z⇒x=+-π/6+πn,n∈Z