(a) \(\int\frac{sin(x - a)}{sin(x + a)}dx\)
= cos 2a ∫ dt – sin 2a ∫ cot t dt
= (cos 2a)t – sin 2a log | sin t | + C1
= (x + a) cos 2a – sin 2a log | sin (x + a) | + C1
= x cos 2a – sin 2a log | sin (x + a) | + a cos 2a + C1
= x cos 2a – sin 2a log | sin (x + a) | + C
( where C = a cos 2a + C1)