If sin−1x=θ+β and sin−1y=θ-β,then1+xy=
sin2θ+sin2β
sin2θ+cos2β
cos2θ+cos2θ
cos2θ+sin2β
We have x=sin(θ+β), andy=sin(θ−β)
⇒1+xy=1+sin(θ+β)sin(θ−β) = 1+sin2θ−sin2β=sin2θ+cos2β