Question

Prove this one.............

Answer 1

Note: We know that sin(2x) = 2sinxcosx

Now,

Given cos x  cos 2x  cos 4x  cos 8x.

$= \ \textgreater \ \frac{2sinxcosx}{2sinx} cos 2x cos 4x cos 8x$

$= \ \textgreater \ \frac{2sin2xcos2x}{4sinx} cos 4x cos 8x$

$= \ \textgreater \ \frac{2sin4xcos4x}{8sinx} cos8x$

$= \ \textgreater \ \frac{2sin8xcos8x}{16sinx}$

$= \ \textgreater \ \frac{sin16x}{16sinx}$



Hope this helps!