JEE Main2017MathematicsIndefinite IntegrationActual
The integral ∫ 1 + 2 cot x cosec x + cot x d x , 0 < x < π 2 is equal to
Options
- A2 log sin x 2 + c
- B4 log sin x 2 + c
- C4 log cos x 2 + c
- D2 log cos x 2 + c
Correct answer
A. 2 log sin x 2 + c
Step-by-step solution
Let I = ∫ 1 + 2 cot x cosec   x + cot x d x     ⇒ I = ∫ 2 cot x cosec x + cosec 2 x + cot 2 x d x ⇒ I = ∫ cosec   x + cot   x 2 d x ⇒ I = ∫ cosec   x + cot   x d x ⇒ I = ∫ cosec   x + cot x d x ⇒ I = log tan x 2 + log sin x + c , where c is the constant of integration. ⇒ I = log sin x 2 cos x 2 · 2 sin x 2 cos x 2 + c ⇒ I = 2 log sin x 2 + c