Address the articulation, Using personality: sin (θ + ϕ) = sin θ cos ϕ + cos θ sin ϕ
= 12/13 x 3/5 + 12/13 x 3/5
= (20+36)/65
= 56/65
or then again sin (θ + ϕ) = 56/65
or then again θ + ϕ) = sin – 1 56/65
Returning the worth of θ and ϕ, we get
cos−1(12/13 ) + sin−1 (13/56)= sin−1 (56/ 65)
Thus Proved.