R.H.S = p2−1p2+1
=(secθ+tanθ)2−1(secθ+tanθ)2+1
=sec2θ+tan2θ+2secθtanθ−1sec2θ+tan2+2secθtanθ+1
[By (a+b)2=a2+b2+2ab]
=(sec2θ−1)+tan2θ+2secθtanθsec2θ+(1+tan2θ)+2secθtanθ
=tan2θ+tan2θ+2secθtanθsec2θ+sec2θ+2secθtanθ
[sec2θ−1=tan2θsec2θ=1+tan2θ]
=2tan2θ+2secθtanθ2sec2θ+2secθtanθ
=2tanθ(tanθ+secθ)2secθ(secθ+tanθ)=tanθsecθ
=sinθcosθ1cosθ
=sinθ = L.H.S