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Question
Prove the following identities:
(cos2A – 1) (cot2A + 1) = −1
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Solution
L.H.S. = (cos2A – 1) (cot2A + 1)
= – (1 – cos2A)(1 + cot2A)
= – sin2A · cosec2A
= `- sin^2"A" xx 1/sin^2"A"`
= – 1
= R.H.S.
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