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Question
Prove the following identity :
`sin^4A + cos^4A = 1 - 2sin^2Acos^2A`
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Solution
`sin^4A + cos^4A = 1 - 2sin^2Acos^2A`
⇒ `sin^4A + cos^4A + 2sin^2Acos^2A = 1`
LHS = `(sin^2A + cos^2A)^2`
= 1 = RHS
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