If , then is equal…

MATHEMATICS · Multi correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

\cos3x\cos^3x+\sin3x\sin^3x=0

, then

x

is equal to: (1)

(2n+1)\frac{\pi}{4}

(2)

(2n-1)\frac{\pi}{4}

(3)

\frac{n\pi}{4}

(4) None of these