Question

Cos^4t - sin^4t = 1 - 2sin^2t

Answer 1

cos(t)^4 - sin(t)^4 = 1 - 2 sin(t)^2
cos(t)^4 = (cos(t)^2)^2 = (1 - sin(t)^2)^2:(1 - sin(t)^2)^2 - sin(t)^4 = ^?1 - 2 sin(t)^2
(1 - sin(t)^2)^2 = 1 - 2 sin(t)^2 + sin(t)^4:1 - 2 sin(t)^2 + sin(t)^4 - sin(t)^4 = ^?1 - 2 sin(t)^2
1 - 2 sin(t)^2 + sin(t)^4 - sin(t)^4 = 1 - 2 sin(t)^2:1 - 2 sin(t)^2 = ^?1 - 2 sin(t)^2
The left-hand side and right-hand side are identical:Answer: (identity has been verified) = Ture

Answer 2

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