CosSin−1(2cos2θ−1)+Cos−1(1−2sin2θ)=
0
1
-1
π2
We know that 2cos2θ−1=1−2sin2θ=cos2θ ∴cossin-1 2cos2θ−1+cos-11−2sin2θ=cossin-1 cos2θ+cos-1cos2θ =cossin-1 sinπ2-2θ+cos-1cos2θ =cosπ2-2θ+2θ =0