Q. Prove that: sin10.sin30.sin50.sin70 = 1/16

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Q. Prove that: (cos5a.sin2a-cos4a.sin3a)/(sin5a.sin2a-cos4a.cos3a) = cot2a Soln: L.H.S. = (cos5a.sin2a-cos4a.sin3a)/(sin5a.sin2a-cos4a.cos3a) Multiply numerator and denominator by 2. = 2(cos5a.sin2a - ...
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