Prove that: ^2 2 x- ^2 6 x= 4 x 8 x - Vidyadip

Question

Prove that: $\cos ^2 2 x-\cos ^2 6 x=\sin 4 x \sin 8 x$

✓

Answer

We have L.H.S $=\cos ^2 2 x-\cos ^2 6 x$
$\left[\because \cos ^2 B-\cos ^2 A=\sin (A+B) \sin (A-B)\right]$
$=\sin 8 x \sin 4 x=$ R.H.S.

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