# Inverse trig substitution integral

1. Feb 28, 2010

### James889

Hi,

I need to integrate the following:

$$\int \frac{x^2}{\sqrt{9-x^2}}$$

So let $$x = 3sin\theta$$
$$\frac{dx}{d\theta} = 3cos\theta$$

So i now have the integral of $$\frac{9sin^2\theta \cdot 3cos\theta}{3cos\theta}$$

How do i go about the integration from here? parts?

2. Feb 28, 2010

### vela

Staff Emeritus
Try simplifying the integrand first.