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∫0πecos⁡xecos⁡x+e−cos⁡xdx=\int_{0}^{\pi} \frac{e^{\cos x}}{e^{\cos x} + e^{-\cos x}} dx =

Solution

✅ Correct Option: 4

Let I=∫0πecos⁡xecos⁡x+e−cos⁡xdxI = \int_0^{\pi} \frac{e^{\cos x}}{e^{\cos x} + e^{-\cos x}}dx.

Using ∫0af(x)dx=∫0af(a−x)dx\int_0^a f(x)dx = \int_0^a f(a-x)dx and cos⁡(π−x)=−cos⁡x\cos(\pi-x) = -\cos x:

I=∫0πe−cos⁡xe−cos⁡x+ecos⁡xdxI = \int_0^{\pi} \frac{e^{-\cos x}}{e^{-\cos x} + e^{\cos x}}dx.

Adding both: 2I=∫0π1 dx=π2I = \int_0^{\pi} 1\ dx = \pi.

So I=π/2I = \pi/2.

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