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The value of $4 \cos 36^{\circ}\cos 72^{\circ}$ is equal to
The value of $4 \cos 36^{\circ}\cos 72^{\circ}$ is equal to
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Logic Tip: A useful identity to memorize for competitive exams is $\cos \theta \cos(60^{\circ}-\theta) \cos(60^{\circ}+\theta) = \frac{1}{4} \cos 3\theta$. Alternatively, memorizing $\cos 36^{\circ}\cos 72^{\circ} = \frac{1}{4}$ will save you significant calculation time.
Updated On: Apr 27, 2026
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The Correct Option is A
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