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Question
Prove the following trigonometric identities.
tan2θ cos2θ = 1 − cos2θ
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Solution
We know that `sin^2 theta + cos^2 theta = 1`
So
`tan^2 theta cos^2 theta = (tan theta xx cos theta)^2`
`= (sin theta/cos theta xx cos theta)^2`
`= sin^2 theta`
`= 1 - cos^2 theta`
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