Prove that sin−1(178)+sin−1(53)=cos−1(8536).Answer: Proved.SolutionLet α=sin−1178, β=sin−153, so sinα=178, sinβ=53 andcosα=1715,cosβ=54Compute cos(α+β):cos(α+β)=cosαcosβ−sinαsinβ=1715⋅54−178⋅53=8560−24=8536Since α+β∈[0,π], α+β=cos−18536, i.e.sin−1178+sin−153=cos−18536cos−18536CBSE Class 12 Board · 2012 · Subjective