Module 19: Lesson 3 Tangents and Circumscribed Angles Vocabulary A tangent is a line that intersects a circle in exactly one place. That place of intersection between the tangent and the circle is called the point of tangency.

Tangent-Radius Theorem If a line is tangent to a circle, then it is perpendicular to a radius drawn to the point of tangency.

Converse of the Tangent-Radius Theorem If a line is perpendicular to a radius of a circle at a point on the circle, then it is tangent to the circle at that point on the circle. Circumscribed Angle Theorem A circumscribed angle of a circle and its associated central angle are supplementary. A C B D

Homework pages 1035-1039 #’s 5-19 (all)