Math, asked by k1aviahmedha, 1 year ago

Cos^4-sin^4 is equal to a)2cos^2a+1 b)2sin^2a +1 c)2sin^2a-1 d)2cos^2a-1

Answers

Answered by sriharshar900

1

cos^4-sin^4 = (cos^2-sin^2)( cos^2+sin^2)
but
cos^2+sin^2=1
so LHS= cos^2-sin^2 = cos^2-(1- cos^2)
=2 cos^2a-1. (d)

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