A Telescoping Tangent Sum

Problem

Given tan4x=33\tan 4x = \dfrac{\sqrt3}{3}, evaluate

sin4xcos8xcos4x+sin2xcos4xcos2x+sinxcos2xcosx+sinxcosx.\frac{\sin 4x}{\cos 8x\cos 4x} + \frac{\sin 2x}{\cos 4x\cos 2x} + \frac{\sin x}{\cos 2x\cos x} + \frac{\sin x}{\cos x}.

Answer

Solution

Difficulty7/10
Topicstrigonometry, Trigonometric Identities, Telescoping

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