wada35

__9.1__ Objectives
Define a circle and its associated parts, and use them in constructions. Define and use the degree measure of arcs. Define and use the length measure of arcs. Prove a theormem about chords and their intercepted arcs.

Definitions
L=M/360.
 * Circle**: is the set of all points in s plane that are equidistant from a given point in the plane known as the center of the circle.
 * Radius**: is a segment from the center of the circle to a point on the circle.
 * Chord**: is a segment whose endpoints line on a circle.
 * Diameter**: is a chord that contains the center of a circle.
 * Semicircle**: is a arc that has endpoints of a diameter.
 * Minor arc**: of a circle is an arc that is less the 180 degres.
 * Major arc**: of a circle is biger the a semicircle which would make it biger the 180 degres.
 * Central angle**: of a circle is an angle in the plane of a circle whose vertex is the center of the circle.
 * Intercepted arc**: of a circle is when the endpoints lie on the sides of the angle and and whose other points lie in the interior of the angle.
 * Minor arc**: is the measure of its centeral angle.
 * Major arc**: is 360 degrees minus the minor arc.
 * Arc length**: If r is the radius of a circle and M is the degree measure of an arc of the circle then the length L of the arc is given by the following