sin left( {frac{pi }{{10}}} right)sin left( { | vedclass

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Question

(c) $\sin \frac{\pi }{{10}}\sin \frac{{3\pi }}{{10}} = \sin 18^\circ .\sin 54^\circ $

$ = \sin 18^\circ .\cos 36^\circ = \frac{{\sqrt 5 - 1}}{4}.\f

Vedclass · Accepted Answer

$1/4$

Vedclass · Answer

(c) $\sin \frac{\pi }{{10}}\sin \frac{{3\pi }}{{10}} = \sin 18^\circ .\sin 54^\circ $

$ = \sin 18^\circ .\cos 36^\circ = \frac{{\sqrt 5 - 1}}{4}.\frac{{\sqrt 5 + 1}}{4} = \frac{1}{4}$.

$\sin \left( {\frac{\pi }{{10}}} \right)\sin \left( {\frac{{3\pi }}{{10}}} \right) = $

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