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**Help with a Trigonometric identity...**

## Homework Statement

(sin x + sin 2x + sin 4x) / (cos x + cos 2x + cos 4x) = tan 2x

## Homework Equations

sin 2x = 2sinxcosx; cos 2x = cos^2x - sin^2x

## The Attempt at a Solution

solving left side,

=[sin x + sin 2x + sin (2x + 2x)]/[cos x + cos 2x + cos (2x+2x)]

=[sin x + sin 2x + 4 sin x*cos^3 x - 4 sin^3 x * cos x] / [cos x + cos 2x + 1 - 6 sin^2 x * cos^2 x]

Cannot go beyond this!

solving right side,

=2 sin x cos x/(cos^2 x - sin^2 x)

=sin 2x/cos 2x