Lines that Intersect Circles 2017

New Vocab Chord: a segment whose endpoints lie on a circle Secant: a line that intersects a circle at two points Tangent: a line that intersects a circle at exactly one point Point of Tangency: the point where the tangent and a circle intersect

Point of Tangency

Types of Circles Congruent Circles: circles that have congruent radii Concentric Circles: coplanar circles with the same center Tangent Circles: two circles that intersect at exactly one point

Example 1: Identify each line or segment that intersects the circle

Tangent Lines Theorem If two segments are tangent to a circle from the same external point, the segments are congruent.

Example 2: Find each length a. x b. RS

Another Tangent Line Theorem If a line is tangent to a circle, then it is perpendicular to the radius.

Homework 9-12, 16-22, 26, 27, 32, 37