Question

ПОМОГИТе срочно cos^2*3x-sin^2*3x-cos4x=0

Answer 1

$cos^{2}3x-sin^{2}3x-cos4x=0\\cos6x-cos4x=0\\-2sin \frac{6x+4x}{2} sin \frac{6x-4x}{2} =0\\-2sin5xsinx=0\\sin5xsinx=0\\\\1)sin5x=0\\5x=\pi n\\x= \frac{\pi n}{5} ,n\in Z;\\\\2)sinx=0\\x=\pi n,n\in Z$