If ( ^ -1 x)= \ ^ -1 ( a b^2-a^2 )\ b > a , then x=
If cot(cos−1x)=sec{tan−1(b2−a2a)}b>a, then x=
Options
A2b2−a2b
Babb2−a2
C2b2−a2a
Dab2−a2
Correct answer
A. 2b2−a2b
Step-by-step solution
Given that,
cot(cos−1x)=sec\left\{\tan ^{-1}\left(\frac{a}{\sqrt{b^2-a^2}}\right)\right\}Since,\cos ^{-1} x=\cot ^{-1} \left(\frac{x}{\sqrt{1-x^2}}\right)andtan−1x=sec−1(1+x2)⇒cot(cot−11−x2x)=sec{sec−11+(b2−a2a)2}⇒1−x2x=b2−a2b2−a2+a2⇒1−x2x=b2−a2bOn squaring both the sides, we get
⇒ 1−x2x2=b2−a2b2⇒x2b2−x2a2=b2−b2x2x2b2+b2x2−x2a2=b2⇒2x2b2−x2a2=b2⇒x2(2b2−a2)=b2⇒x=2b2−a2b