16.6 Circles p.368-369

I. Circle is all the points that are the same distance from a center point – this means every point in a circle is the same distance from the center.
II. Lines through a circle: labeled the same way as line segments – with a line above the two letters
A. Radius: a line segment with one endpoint at the center and the other endpoint on the circle
B. Chord: Line segment with both endpoints on the circle
a. Diameter: a chord that goes through the center of the circle
i. A diameter is twice the length of the radius
ii. A diameter is the longest chord that can be made in a circle

Here is an explanation on how to use a compass from mathsteacher.com