Trigonometric Identities Question 291

Question: If $ \tan \frac{A}{2}=\frac{3}{2}, $ then $ \frac{1+\cos A}{1-\cos A}= $

Options:

A) $ -5 $

B) $ 5 $

C) $ 9/4 $

D) $ 4/9 $

Show Answer

Answer:

Correct Answer: D

Solution:

Given that $ \tan \frac{A}{2}=\frac{3}{2} $ . $ \frac{1+\cos A}{1-\cos A}=\frac{2{{\cos }^{2}}\frac{A}{2}}{2{{\sin }^{2}}\frac{A}{2}}={{\cot }^{2}}\frac{A}{2}={{( \frac{2}{3} )}^{2}}=\frac{4}{9} $ .