DH2004
What is a circle? A circle is a set of points equidistant from a fixed point, called the centre.
DH2004 Circumference The length round a circle. It is a special name for the perimeter of a circle. c
DH2004 Arc One of the two parts between two points on a circumference Arc
DH2004 Radius The distance from the centre of a circle to its circumference. The plural of the term is radii. r
DH2004 Diameter The distance across a circle through its centre. The diameter, d, of a circle is twice its radius, r, so d=2r d
DH2004 Chord A straight line which joins two points on the circumference of a circle Chord
DH2004 Segment The region of a circle enclosed by a chord and an arc. Chord Arc Segment
DH2004 Tangent A straight line that touches a circle at one point only on the circumference. Tangent
DH2004 Sector A portion of a circle enclosed by 2 radii and one of the arcs between them. Sector
DH2004 Semicircle One half of a circle. It can be either of the parts cut off by the diameter. Semicircle
DH2004 Test