40eced70_Geometry_circles__Part
[Description] A line segment with one end point at the center and other end point on the circle [Example] OP is a radius [Properties] The radius is always half the diameter R = d/2. A circle can have an infinite radii. (plural of radius) [Part] 
Radius
C e n t e r
R a d i u s
D i a m e t e r
C i r c u m - f e r e n c e
C h o r d
A r c
S e g m e n t
S e c t o r
S e m i c i r c l e
Geometry:circles
Part