1. The problem asks: Do equal arcs subtend equal angles at the circumference of a circle? 2. Important concept: In a circle, an arc is a portion of the circumference. The angle subtended by an arc at the circumference is the angle formed by two chords from the endpoints of the arc meeting at a point on the circle. 3. The theorem states: Equal arcs of a circle subtend equal angles at the circumference. 4. Explanation: If two arcs have the same length, then the angles they subtend at any point on the circumference (on the same side of the chord) are equal. 5. This is because the angle subtended by an arc at the circumference is proportional to the length of the arc. 6. Therefore, if arc $AB = $ arc $CD$, then angle $AEB = $ angle $CFD$, where $E$ and $F$ are points on the circumference. 7. This property is fundamental in circle geometry and is used to prove many other results. Final answer: Yes, equal arcs subtend equal angles at the circumference.