This document discusses various properties of arcs and angles related to circles: - Arcs are portions of a circle and can be measured in degrees or length. Two arcs are congruent if subtended by congruent chords. - Parallel lines that intersect a circle intercept congruent arcs. - An inscribed angle is equal to half its intercepted arc. A diameter subtends 180 degrees. - An angle inside a circle is half the sum of intercepted arcs. An outside angle is half the difference of arcs. - Secant and tangent theorems relate lengths of chords and segments. - Example problems demonstrate using properties to find measures of unknown arcs.