If sec Θ+tan Θ=p. Show that p2−1p2+1=sin Θ
We have,
LHS=p2−1p2+1=(sin θ+tan θ)2−1(sec θ+tan θ)2+1
=sec2θ+tan2θ+2secθtanθ−1sec2θ+tan2θ+2secθtanθ+1
=(sec2−θ)+tan2θ+2secθtanθsec2+2secθtanθ+(1+tan2θ)
=tan2θ+tan2θ+2secθtanθsec2θ+2secθtanθ+sec2θ
=2tan2θ+2secθtanθ2sec2θ+2secθtanθ
=2tanθ(tanθ+secθ)2secθ(sec+tanθ)
=sinθ=RHS