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Problem Using the identity
sin 4 x = 3 8 − 1 2 cos 2 x + 1 8 cos 4 x or otherwise, if the value of \sin^4 x = \frac{3}{8} - \frac{1}{2} \cos 2x + \frac{1}{8} \cos 4x \text{ or otherwise, if the value of} sin 4 x = 8 3 − 2 1 cos 2 x + 8 1 cos 4 x or otherwise, if the value of sin 4 ( π 7 ) + sin 4 ( 3 π 7 ) + sin 4 ( 5 π 7 ) = a b , where a and b are \sin^4 \left( \frac{\pi}{7} \right) + \sin^4 \left( \frac{3\pi}{7} \right) + \sin^4 \left( \frac{5\pi}{7} \right) = \frac{a}{b}, \text{ where } a \text{ and } b \text{ are} sin 4 ( 7 π ) + sin 4 ( 7 3 π ) + sin 4 ( 7 5 π ) = b a , where a and b are ( a − b ) (a - b) ( a − b ) Browse the problem library