Inverse Trigonometric Functions Question 152

Question: $ {{\tan }^{-1}}\frac{x}{\sqrt{a^{2}-x^{2}}}= $

Options:

A) $ \frac{1}{a}{{\sin }^{-1}}( \frac{x}{a} ) $

B) $ a{{\sin }^{-1}}( \frac{x}{a} ) $

C) $ {{\sin }^{-1}}( \frac{x}{a} ) $

D) $ {{\sin }^{-1}}( \frac{a}{x} ) $

Show Answer

Answer:

Correct Answer: C

Solution:

$ {{\tan }^{-1}}\frac{x}{\sqrt{a^{2}-x^{2}}}={{\tan }^{-1}}( \frac{a\sin \theta }{a\cos \theta } ) $ (Putting $ x=a\sin \theta ) $

$ ={{\tan }^{-1}}(\tan \theta )=\theta ={{\sin }^{-1}}( \frac{x}{a} ) $ .