Evaluate: `intsqrt(4-x^2)\ dx`

Explanation

To evaluate the integral \( I = \int \sqrt{4 - x^2} \, dx \), we can follow these steps:

### Step 1: Identify the Integral Form
We recognize that the integral resembles the standard form \( \sqrt{a^2 - x^2} \). Here, we have \( a^2 = 4 \), which gives us \( a = 2 \).

### Step 2: Use the Trigonometric Substitution
To evaluate the integral, we can use the trigonometric substitution:
\[
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