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Prove the identity:√[(1 – cos 2x)/(1 + cos 2x)] = tan x |
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Answer» Let us consider the LHS √[(1 – cos 2x)/(1 + cos 2x)] As we know that cos 2x = 1 – 2 sin2 x = 2 cos2 x – 1 Therefore, √[(1 – cos 2x)/(1 + cos 2x)] = √[(1 – (1 – 2sin2 x))/(1 + (2cos2x – 1))] = √[(1 – 1 + 2sin2 x)/(1 + 2cos2 x – 1)] = √[2 sin2 x/2 cos2 x] = sin x/cos x = tan x = RHS Thus proved. |
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