tan[sec−1√1+x2]=
1x
x
x√1+x2
tan(sec−1√1+x2)=tan(sec−1√1+tan2 θ) (Putting x=tan θ) =tan(sec−1sec θ)=tanθ=x.
Prove that, Tan theta upon sec theta - 1=Tan theta + sec theta +1 upon Tan theta + sec theta - 1.