Definitions of Parts and Circles

Definitions of Parts and Circles

Introduction: A circle is all points equidistant from one point called the center of the circle. Segments drawn near and through the circle create other geometrical objects which we define. The Lesson: We show circle O below. A circle is named based on the name of the point which is the center. The segment OA is a radius of the circle. Definition: A radius is the segmentcircle itself. connecting (sometimes referred to as the “distance between”) the center and the In the diagram below, we show circle O with radius OA. Segments and lines of interest are: QA: this is a chord RA: this is a chord and it is also a diameter of circle O AP: this is a tangent to the circle Line AR is called a secant Definitions: diameter: the segment connecting two points of the circle and containing the center chord: any segment with endpoints on the circle tangent: any segment, which if extended in either direction, will only intersect the circle once secant: a segment or line which passes through a circle, intersecting at two points In the diagram below, we show circle O. Angles of interest are: angle AOP: this is a central angle angle RAP: this is an inscribed angle angle QAP: this is also an inscribed angle Definitions: A central angle is an angle in a circlevertex at the center of the circle with An inscribed angle is an angle formed by three points on a circle