For a regular polygon with \(n\) sides:
- Interior angle:
\[
\theta_{\text{int}} = \frac{(n-2)\times 180^\circ}{n}
\]
- Exterior angle:
\[
\theta_{\text{ext}} = \frac{360^\circ}{n}
\]
- Number of diagonals:
\[
D = \frac{n(n-3)}{2}
\]
Current polygon:
\(n = \)5,
\(\theta_{\text{int}} = \)108^\circ,
\(\theta_{\text{ext}} = \)72^\circ,
\(D = \)5.