Inverse Trigonometric Functions Question 223

Question: $ {{\sin }^{-1}}\frac{4}{5}+2{{\tan }^{-1}}\frac{1}{3}= $

[ISM Dhanbad 1971]

Options:

A) $ \frac{\pi }{2} $

B) $ \frac{\pi }{3} $

C) $ \frac{\pi }{4} $

D) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

$ {{\sin }^{-1}}\frac{4}{5}={{\tan }^{-1}}\frac{4}{3},2{{\tan }^{-1}}\frac{1}{3}={{\tan }^{-1}}\frac{3}{4}={{\cot }^{-1}}\frac{4}{3} $ and $ {{\tan }^{-1}}x+{{\cot }^{-1}}x=\frac{\pi }{2} $ .