Inverse Trigonometric Functions Question 29

Question: The solution set of the equation $ {{\tan }^{-1}}x-{{\cot }^{-1}}x={{\cos }^{-1}}(2-x) $ will lie in the interval

Options:

A) $ [0,1] $

B) $ [-1,1] $

C) $ [1,3] $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ {{\tan }^{-1}}x $ and $ {{\cot }^{-1}}x $ exist for all $ x\in R $

$ {{\cos }^{-1}}(2-x) $ exists if $ -1\le 2-x\le 1 $ i.e. $ 1\le x\le 3 $

So, the given equation holds for $ 1\le x\le 3 $