Geometry Terms and Definitions

Apothem

The perpendicular distance from the center of a regular polygon to a side of the polygon.

Center of a Circle

The point inside a circle that is the same distance from every point on the circle.

Center of a Regular Polygon

The point that is equidistant from all vertices of a regular polygon.

Central Angle of a Regular Polygon

An angle whose vertex is the center of the regular polygon and whose sides pass through consecutive vertices.

Circle

The set of points in a plane that are a fixed distance from a given point called the center of the circle.

Composite Figure

A plane figure made up of triangles, rectangles, trapezoids, circles, and other simple shapes, or a three-dimensional figure made up of prisms, cones, pyramids, cylinders, and other simple three-dimensional figures.

Geometric Probability

A form of theoretical probability determined by a ratio of geometric measures such as lengths, areas, or volumes.