The value of the integral

Question:

The value of the integral $\int_{-2}^{2} \frac{\sin ^{2} x}{\left[\frac{x}{\pi}\right]+\frac{1}{2}} d x$

(where $[\mathrm{x}]$ denotes the greatest integer less than ${ }^{20} \mathrm{Cr}$ or equal to $\mathrm{x}$ ) is :

  1. 4

  2. 4 – sin4

  3. sin 4

  4. 0


Correct Option: , 4

Solution:

$I=\int_{-2}^{2} \frac{\sin ^{2} x}{\left[\frac{x}{\pi}\right]+\frac{1}{2}} d x$

$I=\int_{0}^{2}\left(\frac{\sin ^{2} x}{\left[\frac{x}{\pi}\right]+\frac{1}{2}}+\frac{\sin ^{2}(-x)}{\left[-\frac{x}{\pi}\right]+\frac{1}{2}}\right) d x$

$\left(\left[\frac{\mathrm{x}}{\pi}\right]+\left[-\frac{\mathrm{x}}{\pi}\right]=-1\right.$ as $\left.\quad \mathrm{x} \neq \mathrm{n} \pi\right)$

$I=\int_{0}^{2}\left(\frac{\sin ^{2} x}{\left[\frac{x}{\pi}\right]+\frac{1}{2}}+\frac{\sin ^{2} x}{-1-\left[\frac{x}{\pi}\right]+\frac{1}{2}}\right) d x=0$

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