Common Core Geometry Practice Test 2026 - Free Geometry Practice Questions and Study Guide

A circumference is defined as the distance around a circle. This measurement is specific to circular shapes, where it represents the boundary or outer edge. The circumference of a circle is calculated using the formula \( C = 2\pi r \) or \( C = \pi d \), where \( r \) is the radius and \( d \) is the diameter.

While triangles, squares, and rectangles all have perimeters—referring to the total distance around any polygon—they do not have circumferences, as that term specifically applies to circles. Each of these other shapes is comprised of straight edges, and their outlines are measured in a different way. Thus, the correct identification of the shape that has a circumference is the circle.