Learn polygon basics and angle formulas, with clear proofs and worked examples.

Introduction

What polygons are and how to recognize them.

1. Polygons (Basics)
2. Types of Polygons
3. Is this a Polygon
   
   

Interior angles

Learn the interior-angle formula and practice finding missing angles.

1. Sum of Interior Angles of a Polygon (Proof)
2. Find Missing Interior Angles of a Polygon (Examples)
3. Why Regular and Irregular Polygons Have Different Angle Formulas?
   
   

Exterior angles

Understand exterior angles and the exterior-angle sum for different types of polygons.

1. Sum of Exterior Angles of Regular Polygons (Proof)
2. Sum of Exterior Angles of Convex Polygons (Proof)
3. Sum of Exterior Angles of Concave Polygons (Example)
4. Exterior Angles of a Polygon (Examples)
   
   

Interior and exterior angles

Practice problems that combine both interior and exterior angles (including concave cases).

1. Find Missing Interior & Exterior Angles of Regular Polygons (Examples)
2. Interior & Exterior Angles of a Polygon (Examples)
3. Interior & Exterior Angles of a Concave Polygon (Example)