Circles
Distinguish circle elements and describe their relative positions.
Meaning
A circle consists of points in a plane at a fixed distance from its center. That distance is the radius; a diameter is a chord through the center and twice the radius.
Example
A radius of 4 cm gives a diameter of 8 cm. A 90-degree sector's arc is one quarter of the circumference. A diameter joins two radii across the center, giving 4+4=8 cm. In the same circle, dividing a full 360-degree turn into four 90-degree parts also divides the circumference into four equal arcs. A chord is a segment joining two circle points; an arc follows the circumference. Do not confuse their lengths.
Practice for this concept
Scope and references
Topics
Centers, radii, diameters, chords, arcs, sectors, tangents
Learning goal
Distinguish circle elements and describe their relative positions.
Helpful background
Explore equal distance from a center and angles.
Circles
These choice exercises use stated geometric conditions. They do not establish construction, drawing, spatial manipulation, written proof, or mastery of the whole geometry area.