Parts of a Circle

• Center of a Circle EX: A

• A radius is a segment whose endpoints are the center and any point on the circle. EX: HA or FA

• The diameter is a chord that contains the center of the circle. EX: HF

• A chord is a segment whose end points are on the circle. EX: DG

• A secant is a line that intersects a circle at two points. EX: BD

• A tangent is a line in the plane of a circle that intersects the circle in exactly one point. EX: JB

• A ​point of tangency is where the tangent and circle intersect. EX: H

Determining if a line is tangent to a circle

A tangent to a circle will be perpendicular to the radius of a circle at the point of tangency

Tangent segments of a circle with the same external endpoint are congruent