If tanθ+sinθ=m and tanθ−sinθ=n, then
m2−n2=4mn
m2+n2=4mn
m2−n2=m2+n2
From the given relations,
m+n=2tanθ,m−n=2sinθ
thus , m2−n2=4tanθsinθ-----i
also , mn=tan2θ−sin2θ=sinθtanθ----ii
From Eqs. (i) and (ii), we get m2−n2=4mn