A Staircase Trigonometric Inequality

Problem

Let 0<x<y<z<π20<x<y<z<\dfrac{\pi}2. Prove that

π2+2sinxcosy+2sinycosz>sin2x+sin2y+sin2z.\frac{\pi}2+2\sin x\cos y+2\sin y\cos z>\sin 2x+\sin 2y+\sin 2z.

Answer

Solution

Difficulty8/10
Topicstrigonometry, Trigonometric Identities, Estimation, inequality

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