This document covers key concepts about circles and arcs. It defines important circle terminology like central angle, arc, minor arc, major arc, and congruent arcs. It provides examples demonstrating how to find measures of arcs and angles using properties of circles, congruent arcs, and the Pythagorean theorem. Examples are worked through step-by-step showing calculations to find arc measures, angles, and distances on circles. Review questions at the end test understanding of applying circle properties and theorems to solve measurement problems.