# Geometry

In Glogpedia

Last updated 4 years ago

Discipline:
Math
Subject:
Geometry
3,4,5,6,7,8   Circle

A circle with circumference (C) in black, diameter (D) in cyan, radius (R) in red, and centre (O) in magenta.

Geometry

Sector: a region bounded by two radii and an arc lying between the radii.Segment: a region, not containing the centre, bounded by a chord and an arc lying between the chord's endpoints.Semicircle: an arc that extends from one of a diameter's endpoints to the other. In non-technical common usage it may mean the diameter, arc, and its interior, a two dimensional region, that is technically called a half-disk. A half-disk is a special case of a segment, namely the largest one.

Vocabulary of Circles

Centre: the point equidistant from the points on the circle.Chord: a line segment whose endpoints lie on the circle.Diameter: a line segment whose endpoints lie on the circle and which passes through the centre; or the length of such a line segment, which is the largest distance between any two points on the circle. It is a special case of a chord, namely the longest chord, and it is twice the radius.Radius: a line segment joining the centre of the circle to any point on the circle itself; or the length of such a segment, which is half a diameter.

Practise what you learned

Introduction to Circles

Chord, secant, tangent, radius, and diameter,sector arc, and segment