Question #c38f4

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Answer 1 · 2016-10-24T22:35:40

Substitute in #cos^2(x) = 1-sin^2(x)#.

Using the identity

#sin^2(x) + cos^2(x) = 1#

we can subtract #sin^2(x)# from both sides to obtain

#cos^2(x) = 1-sin^2(x)#.

With that:

#cos^2(x) - sin^2(x) = (1-sin^2(x))-sin^2(x))#

#= 1-2sin^2(x)#