A semicircle is half of a full circle with endpoints at the diameter. The measure of a semicircle is 180 degrees. A minor arc is smaller than a semicircle while a major arc is larger. The central angle is an angle with its vertex at the circle's center. The measure of a minor arc or major arc is equal to the measure of its central angle or 360 minus the minor arc's measure, respectively. Two arcs are adjacent if they share one point and their combined arc measure is the sum of the individual arcs.

2. Semicircle A semicircle is an arc of a circle whose endpoints are the endpoints of the diameter.

3. The degree measure of a semicircle is 180.

4. Minor Arc An arc of a circle that is smaller than a semicircle.

5. Major Arc An arc of a circle that is larger than a semicircle.

6. Central Angle An angle whose vertex is the center of the circle.

9. The measure of the minor arc is the measure of its central angle in degrees.

11. The measure of the major arc is 360 minus the measure of its minor arc.

13. In the same circle or in congruent circles, two minor arcs are congruent iff their central angles are congruent.

15. Two arcs of a circle are adjacent nonoverlapping arcs iff they have exactly one point in common.

17. The measure of an arc formed by two adjacent non overlapping arc is the sum of the measures of those two arcs.

20. A chord corresponds to an arc iff its endpoints are on the circle and on the central angle of the given arc.

22. Properties you have to keep in mind...

23. Two minor arcs in the same or congruent circles are congruent if their corresponding chords are congruent.

24. If a diameter of the circle is perpendicular to the chord, then the line bisects the chord and its arc.

26. Two chords are equidistant from the center iff they are congruent.

28. ASSIGNMENT On ¼ sheet of paper, answer page 303, CYU 1-5