$\int\limits_{-\pi}^{\pi}\frac{e^{\sin x}}{e^{\sin x}+e^{-\sin x}}dx$ is equal to |
0 $\frac{\pi}{2}$ $\pi$ $\frac{\pi}{4}$ |
$\pi$ |
The correct answer is Option (3) → $\pi$ $ I=\int_{-\pi}^{\pi}\frac{e^{\sin x}}{\,e^{\sin x}+e^{-\sin x}\,}\,dx $ $ \frac{e^{\sin x}}{e^{\sin x}+e^{-\sin x}} =\frac{1}{1+e^{-2\sin x}} $ $ f(x)=\frac{1}{1+e^{-2\sin x}},\; f(-x)=\frac{1}{1+e^{2\sin x}} $ $ f(x)+f(-x)=1 $ $ I=\int_{-\pi}^{\pi}f(x)\,dx =\int_{-\pi}^{\pi}\frac{1}{2}(f(x)+f(-x))\,dx $ $ I=\frac{1}{2}\int_{-\pi}^{\pi}1\,dx $ $ I=\frac{1}{2}(2\pi)=\pi $ The value of the integral is $\pi$. |