1. Circles: Vocabulary and Properties

2. Circle A set of all points in a plane at a given distance from a given point called the center .

3. WHERE? Interior of the circle? Exterior of the circle? On the Circle?

4. Radius A segment from a point on the circle to the center of the circle.

5. EXAMPLES

6. Chord A segment whose endpoints lie on the circle.

7. Diameter A chord passing through the center of a circle.

8. Secant A line that contains a chord.

9. EXAMPLES

10. Congruent Circles Two circles whose radii have the same measure.

11. EXAMPLES

12. Concentric Circles Two coplanar circles having the same center.

13. EXAMPLES

14. Tangent A line in the plane of the circle that intersects the circle in exactly one point.

15. EXAMPLES

16. A polygon is inscribed in a circle if every vertex of the polygon is a point on a circle.

17. The triangle, octagon and square are inscribed in the circle.

18. ... and the circle is circumscribed about the polygon.

19. Tangent slim, infinite (adjective) meets, touches, strokes (verb) but only at one point (phrase) PART OF A CIRCLE (definition/description)