How do you prove $sin^2 theta-cos^2 theta=2sin^2 theta-1$ ?

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Answer 1 · 2016-04-13T18:34:46

Use the pythagorean identity $sin^2theta + cos^2theta = 1$ .

Manipulating the identity, we get: $sin^2theta - 1 = -cos^2theta$

$sin^2theta + sin^2theta - 1 =$

$2sin^2theta - 1 = ->$ Identity proved

Hopefully this helps!

How do you prove sin^2 theta-cos^2 theta=2sin^2 theta-1sin^2 theta-cos^2 theta=2sin^2 theta-1?