Evaluate: `intsqrt(a^2-x^2)\ dx`

Explanation

To evaluate the integral \(\int \sqrt{a^2 - x^2} \, dx\), we can use trigonometric substitution. Here’s a step-by-step solution:

### Step 1: Substitute \(x = a \sin \theta\)
Let \(x = a \sin \theta\). Then, the differential \(dx\) is given by:
\[ dx = a \cos \theta \, d\theta \]

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