1. Circle Basics
Advanced Geometry

2. CIRCLE
A circle is the locus or set of all points in a plane that are equidistant from a given point, called the center.

3. RADIUS
The distance from the center to a point on the circle is the radius of the circle. All radii of a circle are congruent.

4. CONGRUENT CIRCLES
Two circles are congruent if they have the same radius.

5. CHORD
A chord is a segment whose endpoints are points on the circle.

6. DIAMETER
The distance across the circle, through its center, is the diameter of the circle. A chord that passes through the center and is made up of collinear radii.

7. The diameter is twice the radius.

8. SECANT
A secant is a line that intersects a circle in two points.

9. SECANT The diameter is a chord, but it is part of a secant.
If the diameter was extended on both sides, then it would be called a secant.

10. TANGENT
A tangent is a line in the plane of a circle that intersects the circle in exactly one point.

11. POINT OF TANGENCY
The point at which a tangent line intersects the circle to which it is tangent is the point of tangency.

12. IDENTIFY THE PARTS OF THE CIRCLEK C B J D E H F G

13. INTERIOR AND EXTERIOR OF A CIRCLE
The interior of a circle consists of the points that are inside the circle. The exterior of a circle consists of the points that are outside the circle.

14. Example
Circles B and E have radii of 8 cm & 6 cm respectively, and CD is 3 cm. Use this information to determine the missing values. BC EA
Perimeter of BGEH AF
Perimeter of ∆BGE