A Product of Sines

8/10trigonometryAM-GMinequality

Problem

For every positive integer nn and real θ\theta, prove that

sinθsin2θsin2nθ(32)n.\left|\sin\theta \cdot \sin 2\theta \cdots \sin 2^n\theta\right| \le \left(\frac{\sqrt3}{2}\right)^n.

Answer

Solution

Difficulty8/10
Topicstrigonometry, AM-GM, inequality

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