The correct options are
A 1sin(a−b)logsin(x−a)sin(x−b).
B 1sin(b−a)logsin(x−b)sin(x−a).
I=∫1sin(x−a)sin(x−b)dx.
Substitute, a−b=(x−b)−(x−a)⇒sin(a−b)=sin(x−b)cos(x−a)−cos(x−b)sin(x−a) ... (i)
∴I=1sin(a−b)∫sin(x−b)cos(x−a)−cos(x−b)sin(x−a)sin(x−a)sin(x−b)dx by (i) =1sin(a−b)∫[cot(x−a)−cot(x−b)]dx=1sin(a−b)[logsin(x−a)−logsin(x−b)] =1sin(a−b)logsin(x−a)sin(x−b).