Q.

Considering the principal values of the inverse trigonometric functions, sin–1(32x+121–x2), –12<x<12, is equal to          [2025]

1 –5π6–sin–1x  
2 π4+sin–1x  
3 5π6–sin–1x  
4 π6+sin–1x  

Ans.

(4)

Let sin–1x=θ,–π4<θ<π4

⇒ x=sinθ

Now, sin–1(32x+121–x2)

=sin–1(sinθ cosπ6+cosθ sinπ6)

=sin–1(sin(θ+π6))=θ+π6=sin–1x+π6