1.

`int (dx)/(sin(x-a)sin(x-b)`A. `sin(b-a)log|(sin(x-b))/(sin(x-a))|+C`B. `cosec(b-a)log|(sin(x-a))/(sin(x-b))|+C`C. `cosec(b-a)log|(sin(x-b))/(sin(x-a))|+C`D. `sin(b-a)log|(sin(x-a))/(sin(x-b))|+C`

Answer» Correct Answer - A
`I = int(dx)/(sin(x-a)sin(x-b))`
`= (1)/(sin(b-a))int(sin(b-a))/(sin(x-a)sin(x-b))dx`
`= (1)/(sin(b-a))int(sin(x-a-x+b))/(sin(x-a)sin(x-b))dx`
`= (1)/(sin(b-a))int(sin{(x-a)-(x-b)})/(sin(x-a)sin(x-b))dx`
`= (1)/(sin(b-a)) int(sin(x-a)cos(x-b)-cos(x-a)sin(x-b))/(sin(x-a)sin(x-b))dx`
`= (1)/(sin(b-a)) int[cot(x-b)-cot(x-a)]dx`
`= (1)/(sin(b-a)) [log|sin(x-b)|-log|sin(x-a)|]+C`
`= cosec (b-a)log|(sin(x-b))/(sin(x-a))|+C`


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