MCQ
$\int\limits_0^{\frac{\pi }{2}} {\frac{{{3^{\sin x}}}}{{{3^{\sin x}} + {3^{\cos x}}}}} \,dx =\ .........$
  • A
    $2$
  • $\frac{\pi }{4}$
  • C
    $\frac{\pi }{2}$
  • D
    $\pi $

Answer

Correct option: B.
$\frac{\pi }{4}$
$ I = \int_{0}^{\frac {\pi}{2}} \frac {3^{\sin x}}{3^{\sin x}+3^{\cos x}}dx \ ......... (1)$
$= \int_{0}^{\frac {\pi}{2}} \frac {3^{\sin x^(\frac{\pi}{2}-x)}}{3^{\sin^(\frac{\pi}{2}-x)}+3^{\cos^(\frac{\pi}{2}-x)}}dx$
$= \int_{0}^{\frac {\pi}{2}} \frac {3^{\cos x}}{3^{\sin x}+3^{\cos x}}dx\ ......... (2)$
સમી $(1)$ અને $(2)$ નો સરવાળો કરતા
$2 \ I=\int_{0}^{\frac {\pi}{2}}1 \ \ dx $
$ \therefore 2 I = [x]_0^{\frac {\pi}{2}}$
$ \therefore 2I= \frac {\pi}{2}$
$ \therefore I = \frac {\pi}{4}$

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