The interior angles of a polygon are in arithmetic progression. The smallest angle is `120^@` and the common difference is `5^@` Find the number of sides of the polygon

Explanation

To solve the problem step by step, we will follow the logic outlined in the video transcript and derive the solution systematically.

### Step 1: Define Variables
Let the number of sides of the polygon be \( n \). The interior angles of the polygon are in arithmetic progression (AP).

### Step 2: Identify the Angles
The smallest angle \( A \) is given as \( 120^\circ \) and the common difference \( D \) is \( 5^\circ \). Therefore, the angles can be expressed as:
- First angle: \( A = 120^\circ \)
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