The integral is .

Rewrite the integral as   .

Consider .

Here the integrand function is an odd function.

From the symmetric property of the integrals, .

Consider .

Determine the integral interms of an area.

Find the area of the region under the curve using graphing utility.

Graphically the area of the region under the curve is .

.

Required integral is three times the area of the semicircle.

Therefore, .

Substitute results of  and  in .

.