1)

$\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}  \log\left(\frac{2-\sin x}{2+\sin x}\right)dx$  is equal to 


A) 1

B) 3

C) 2

D) 0

Answer:

Option D

Explanation:

We have ,l=$\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}  \log\left(\frac{2-\sin x}{2+\sin x}\right)dx$ 

Let   $f(x)=\log\left(\frac{2-\sin x}{2+\sin x}\right)$

Then,   $f(-x)=\log\left(\frac{2-\sin (-x)}{2+\sin (-x)}\right)$

$=\log\left(\frac{2+\sin x}{2-\sin x}\right)=\log\left(\frac{2-\sin x}{2+\sin x}\right)^{-1}$

 $=-\log\left(\frac{2-\sin x}{2+\sin x}\right)=-f(x)$

 then, f(x) is odd function.

$\therefore$    $\int_{-\pi/2}^{\pi/2}  f(x) dx=0$

   [ $\because $  f(x) is an odd function, then $\int_{-a}^{a}  f(x) dx=0$]