(a) A radius is a segment that joins the center of a circle to a point on the circle
From the diagram, the radius is:

(b) A diameter is a segment that passes through the center of the circle and joins two points on a circle.
From the diagram, the diameter is:

(c) A chord is a segment that does not pass through the center of the circle and joins two points on a circle.
From the diagram, the chord is:

(d) The relation between the lengths of the radius and the diameter is:

From items a and b:

Substituting with FE = 10 units:
