The correct option is C 2a1−a2
tan[12sin−1(2a1+a2)+12cos−1(1−a21+a2)]
=tan[12sin−1(2tanθ1+tan2θ)+12cos−1(1−tan2θ1+tan2θ)]
(Let a=tanθ)
=tan[12sin−1(sin2θ)+12cos−1(cos2θ)]
=tan(2θ)=tan2θ=2tanθ1−tan2θ=2a1−a2
Trick : Put a=0, then tan(0+0)=0; which is given by (a) and (c). Again put a=1, then tan(π4+π4)=∞, which is given by (c).