Trigonometric Identities Question 372

Question: $ \frac{{{\sin }^{2}}A-{{\sin }^{2}}B}{\sin A\cos A-\sin B\cos B}= $

[MP PET 1993]

Options:

A) $ \tan (A-B) $

B) $ \tan (A+B) $

C) $ \cot (A-B) $

D) $ \cot (A+B) $

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Answer:

Correct Answer: B

Solution:

$ \frac{{{\sin }^{2}}A-{{\sin }^{2}}B}{\sin A\cos A-\sin B\cos B}=\frac{2,\sin ,(A+B),\sin ,(A-B)}{\sin ,2A-\sin ,2B} $ $ =\frac{2,\sin ,(A+B),\sin ,(A-B)}{2,\cos ,(A+B),\sin ,(A-B)}=\tan ,(A+B) $ .