JEE Main & Advanced Mathematics Inverse Trigonometric Functions Question Bank Mock Test - Inverse Trigonometric Functions

  • question_answer
    If\[a{{\sin }^{-1}}x-b{{\cos }^{-1}}x=c,\]then\[a{{\sin }^{-1}}x+b{{\cos }^{-1}}x\]is equal to

    A) 0                     

    B) \[\frac{\pi ab+c(b-c)}{a+b}\]

    C) \[\frac{\pi }{2}\]            

    D) \[\frac{\pi ab+c(a-b)}{a+b}\]

    Correct Answer: D

    Solution :

    [d] \[a{{\sin }^{-1}}x-b{{\cos }^{-1}}x=c\] We have b \[{{\sin }^{-1}}x+b{{\cos }^{-1}}x=\frac{b\pi }{2}\] Adding \[(a+b)\]\[{{\sin }^{-1}}x=\frac{b\pi }{2}+c\] Or \[{{\sin }^{-1}}x=\frac{\left( \frac{b\pi }{2} \right)+c}{a+b}=\frac{b\pi +2c}{2(a+b)}\] \[\therefore {{\cos }^{-1}}x=\frac{\pi }{2}-\frac{b\pi +2c}{2(a+b)}=\frac{\pi a-2c}{2(a+b)}\] \[\Rightarrow a{{\sin }^{-1}}x+b{{\cos }^{1}}x=\frac{\pi ab+c(a-b)}{a+b}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner