Diameter = a straight line passing from side to side through the center of a body or figure, especially a circle or sphere.a unit of linear measurement of magnifying power.
F-O is Radius
Radius = a straight line from the center to the circumference of a circle or sphere.
F-B is Arc
Arc = a part of the circumference of a circle or other curve.
"the point where a tangential line touches the arc of a circle"
E-C-B-D is Chord
Chord = A chord of a circle is a straight line segment whose endpoints both lie on a circular arc. The infinite line extension of a chord is a secant line, or just secant. ... A chord that passes through a circle's center point is the circle's diameter. The word chord is from the Latin chorda meaning bowstring.
