If (tanθ+sinθ)=m and (tanθ−sinθ)=n, prove that
(m2−n2)2=16mn.
m=(tanθ+sinθ)n=(tanθ−sinθ)m2−n2=(m+n)(m−n)=(tanθ+sinθ+tanθ−sinθ)(tanθ+sinθ−(tanθ−sinθ))=(2tanθ)(tanθ+sinθ−tanθ+sinθ)=(2tanθ)(2sinθ)=4tanθ sinθ(m2−n2)2=16sin2θ tan2θ−−−(1)mn=(tanθ+sinθ)(tanθ−sinθ)=tan2θ−sin2θ=sin2θ(1cos2θ−1)=sin2θ(1−cos2θcos2θ)=sin2θ(sin2θcos2θ)=sin2θ tan2θ16mn=16sin2θ tan2θ−−−−(2)From (1) and (2),(m2−n2)2=16mn