Circles

• Chord : a segment whose endpoints are on a circle
• Diameter : is a chord that slices the circle in half
• Tangent : a line in the plane of a circle that intersects the circle in exactly one point, the point of tangency
• Radius : half of a diameter
• Central Angle : an angle whose vertex is the center of the circle
• Circular Arc : portion of a circle. The measure of a circular arc is the measure of its central angle
• Minor arc : less than 180
• Major arc : larger than 180 and does not lie on the minor arc
• The measure of the entire circle is 360
• The measure of a semicircle is 180
• Perpendicular Chord Bisector Theorem : if a diameter of a circle is Perpendicular to a chords then the diameter bisects the chord and its arc