CentilitreSymbol: cl. A unit of volume equivalent to one-hundredth of a litre. |
CentimetreSymbol: cm. A unit of linear measure, one hundredth of a metre. |
CentreThe middle point. |
ChordA straight line segment joining two points on a circle or other curve. |
CircleA set of points in a plane at a fixed distance (the radius) from a fixed point (the centre) also in the plane; alternatively the path traced by a single point travelling in a plane at a fixed distance (the radius) from a fixed point (the centre) in the same plane. One half of a circle cut off by a diameter is a semi-circle. |
CircumferenceThe length of a circle (its perimeter). If the radius of a circle is r units, and the diameter d units, then the circumference is 2 ?r, or ?d units. For a sphere the circumference is the length of a 'great circle' on the sphere - this is like the equator on our planet. |
ClockwiseIn the direction in which the hands of clock travel, and the direction bearings and angles are usually measured. Anti-clockwise or counter-clockwise are terms used for the opposite direction. |
Co-ordinateA position in 2D or 3D space, represented by numbers, letters or both. See 'Cartesian co-ordinates'. |
Complementary NumbersTwo angles with the sum of 90 degrees . |
Compound MeasuresMeasures with two or more dimensions. Examples: speed calculated as distance ÷ time; density calculated as mass ÷ volume; car efficiency measured as litres per 100 kilometres; and rate of inflation measured as percentage increase in prices. |