Key Concepts: Areas of Regular Polygons and Composite Figures

Area of a Regular Polygon

A = ½aP

where a is the apothem (distance from center to a side) and P is the perimeter.

Key Definitions

• Center: equidistant from all vertices.
• Radius: segment from center to a vertex.
• Apothem: perpendicular segment from center to a side.
• Central angle of a regular n-gon = 360°/n.

Composite Figures

Break a composite figure into non-overlapping simple shapes. Find each area and add (or subtract for holes).