definitions of words ok Tools A B radius segment whose end points are the center and a point on the circle chord line segemnt whose endpoints are on the circle diameteter chord that passes through the middle of a cirlce(lenghtth the diameter is twice the lenghth of the radius secant line that intersects a circle in two different points. Every secant contains a chord tangent line that intersects a circle in exactly one point. Point of contact is called the point of tangency. A radius drawn tot he point of tangency is perpendicular to the tangent at that point If two tangent segments are drawn to a circle from the same point they have the same lenghth inscribed each vertex of the polygon is a point onthe circle. Circle is said to be circumscribed about the polygon semi cirrcle arc that is one half the circle. Degree measure is 180 degrees minor arc arc tha t is less thatn a semi circle . Degree measurent is between 0 and 180 degrees major acr is greater than the semi circle. Degree measure is between 180 and 360 degrees congruent arcs arcs in same circle or congruent circles that have hte same degree measure central angle angle whose vertex is at the center of a circle degree measure of a minor arc is the degree measure of the central angle that intercepts it equal chords have equal arcs arc between parallel chords are equal equal chords are the same distance from the center Chords that are the same distance from the center are equal the measure of the inscribed angle is one half the measure of its intercepted arc the measure of an angle fromed by a tanfent and a chord drawn to the point of tangency is one half the measure of it intercepted arc