A central angles is an angle formed by two radii and vertex at the center of a circle. [br][br]What do you notice about the measure of the central angle and the angle of the intercepted arc, shown as [math]\text{m\widehat{BC}}[/math] below?

An inscribed angle is an angle formed by two intersecting chords or secants with its vertex "on" the circle. [br][br]What do you notice about the measure of the inscribed angle, [math]D[/math], and the angle of the intercepted arc [math]\text{\widehat{BC}}[/math] below?

An angle formed by an intersecting tangent and chord has its vertex "on" the circle. [br][br]What do you notice about the measure of this special inscribed angle, [math]B[/math], and the angle of the intercepted arc, [math]\text{\widehat{BC}}[/math] shown below?

Exterior angles are formed by two secants, a secant and a tangent, or two tangents, has its vertex outside the circle if the lines intersect outside the circle. [br][br]What do you notice about the measure of the exterior angle, [math]F[/math], and the angle of the two intercepted arcs [math]\text{\widehat{BD}}[/math] (minor arc) and [math]\text{\widehat{CE}}[/math] (major arc) shown below?