$\int_{0}^{\frac{\pi}{2}}\left(e^{\sin x}-e^{\cos x}\right) d x=$
$\int_{0}^{\frac{\pi}{2}}\left(e^{\sin x}-e^{\cos x}\right) d x=$
- $\frac{1}{2}$
- $0$
- $1$
- $\frac{\pi}{4}$
Solution
$\begin{aligned}
\text {Let } I &=\int_{0}^{\frac{\pi}{2}}\left(e^{\sin x}-e^{\cos x}\right) d x ....(1)\\
&=\int_{0}^{\pi / 2} e^{\sin \left(\frac{\pi}{2}-x\right)}-e^{\cos \left(\frac{\pi}{2}-x\right)} \mathrm{dx} \\
&=\int_{0}^{\pi / 2} e^{\cos x}-e^{\sin x} d x....(2)
\end{aligned}$
Adding equation (1) \& (2) we get
$\begin{array}{l}
2 I=\int_{0}^{\pi / 2}\left(e^{\sin x}-e^{\cos x}-e^{\cos x}-e^{\sin x}\right) d x \\
2 I=0 \Rightarrow I=0
\end{array}$
Asked in: MHT CET 2020 (15 Oct Shift 1)
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