(i) sin2θ+1(1+tan2θ)=1 (ii) 11+tan2θ+11+cot2θ=1
(i) sin2θ+1(1+tan2θ)=1LHS=sin2θ+1(1+tan2θ)=sin2θ+1(1+sin2θcos2θ)=sin2θ+1(cos2θ+sin2θcos2θ)=sin2θ+cos2θcos2θ+sin2θ=sin2θ+cos2θ1=sin2θ+cos2θ=1=RHS
(ii) 11+tan2θ+11+cot2θ=1LHS=11+tan2θ+11+cot2θ=11+tan2θ+11+1tan2θ=11+tan2θ+11+tan2θtan2θ=11+tan2θ+tan2θ1+tan2θ=1+tan2θ1+tan2θ=1=RHS