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Question
Prove that:
2 sin2 A + cos4 A = 1 + sin4 A
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Solution
L.H.S. = 2 sin2 A + cos4 A
= 2 sin2 A + (1 – sin2 A)2
= 2 sin2 A + 1 + sin4 A – 2 sin2 A
= 1 + sin4 A = R.H.S.
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