Question: $ \frac{\tan A+\tan B}{\cot A+\cot B} $ is equal to
Options:
A) $ \cot A\cot B $
B) $ \sec A\text{cosec B} $
C) $ \tan A\tan B $
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
- $ \frac{\tan A+\tan B}{\cot A+\cot B}=\frac{\frac{\sin A}{\cos A}+\frac{\sin B}{\cos B}}{\frac{\cos A}{\sin A}+\frac{\cos B}{\sin B}} $
$ =\frac{\frac{\sin A\cdot \cos B+\cos A\cdot \sin B}{\cos A\cdot \cos B}}{\frac{\cos A\cdot \sin B+\sin A\cdot \cos B}{\sin A\cdot \sin B}} $
$ =\frac{\sin A\cdot \sin B}{\cos A\cdot \cos B}=\tan A\cdot \tan B $