CIRCLES
A circle is a figure for which each point is an equal distance from its center. In the diagram, O is the center of the circle.
The radius of a circle is the straight-line distance from its center to any point on the circle. All radii of one circle have equal
lengths. In the figure above, OA is a radius of circle O.
A chord is a line segment that connects any two points on a circle. Segments AB and AC are both chords. The largest chord that may
be drawn in a circle will be a diameter of that circle.
A diameter of a circle is a chord that passes through the circle’s center. All diameters are the same length and are equal to twice the
radius. In the figure above, AC is a diameter of circle O.