This document defines and describes the key parts of a circle, including the centre, circumference, diameter, arc, radius, chord, segment, sector, and tangent. The centre is in the middle. The circumference measures around the outside. The diameter goes through the centre and across. The arc is curved on the outer edge. The radius is half the diameter. The chord goes from edge to edge without passing through the centre. A segment is cut from the circle by a chord. A sector is shaped like a pizza slice defined by lines from the centre to the edge. A tangent touches but does not intersect the edge.

1. LO : To be able to name the
circle parts
Parts of a circle

2. Centre
A part is in the middle
of the circle.

3. Circumference
A part that only measures round the
outside of the circle.

4. Diameter
A part that goes through from edge to centre to
the another edge.

5. Arc
A part that is curved on outer edge of the circle.

6. Radius
A part that is halve of the
diameter.

7. Chord
A part that goes from edge to edge but does not
go through the centre.

8. Segment
•A part that which is cut from
the circle by a "chord" (a
line between two points on
the circle).
•A part that goes from edge to
edge but does not go through
the centre but the line that
you drew, is that you shade in
the part as shown.

9. Sector
•A part that the 2
lines going out
from the centre
to the edge.
•Think of it a
pizza slice

10. Tangent
A part that touches the
edge of the circle.