Prove: (x-y) (x+y) = 1+ x y 1- x y .

MATHEMATICS · Subjective · CBSE · Mathematics · Introduction to Trigonometry · Introduction to Trigonometry

Problem

Prove: cos⁡(x−y)cos⁡(x+y)=1+tan⁡xtan⁡y1−tan⁡xtan⁡y.\frac{\cos(x-y)}{\cos(x+y)}=\frac{1+\tan x\tan y}{1-\tan x\tan y}.

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