Evaluate: `int1/(sqrt(x^2+a^2))\ dx`

Explanation

To evaluate the integral \( I = \int \frac{1}{\sqrt{x^2 + a^2}} \, dx \), we will use a trigonometric substitution. Here’s the step-by-step solution:

### Step 1: Trigonometric Substitution
Let \( x = a \tan(\theta) \). Then, the differential \( dx \) can be expressed as:
\[ dx = a \sec^2(\theta) \, d\theta \]

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