Edexcel GCSE Mathematics key terms

A shape's property of matching itself when reflected in a mirror line.

A polygon with all sides equal in length and all interior angles equal in size.

Units that measure compatible types of quantity and can therefore be converted between one another, such as metres and centimetres.

The proportion of trials in which an outcome occurs: frequency of the outcome divided by the total number of trials.

The amount left over when one whole number does not divide exactly into another.

A single solution obtained twice when a quadratic contains two identical linear factors, such as $(x-4)^2=0$.

Using an option again after it has already been chosen.

Returning a selected item before the next selection so that the original collection is restored.

A sample that reflects the important characteristics of the population reasonably well.

The single vector that has the same overall effect as two or more vectors applied in sequence.

A calculation that works backwards from a final value and a percentage change to find the original value.

A quadrilateral with four equal sides.

An angle of 90°, formed where two lines meet perpendicularly.

A triangle containing one angle of exactly $90^\circ$.

A transformation that changes the position or orientation of a shape without changing its size or shape.

A value of $x$ for which a quadratic expression equals zero; on its graph, this is where the curve meets the $x$-axis.

A turn through a specified angle about a fixed centre.

A shape's property of matching itself after a turn of less than $360^\circ$ about a centre.

The process of replacing a number with a nearby value at a stated place value or degree of accuracy.

A smaller group selected from a population to provide information about it.

The complete set of all possible outcomes of an experiment.

A list or other record of the members of a population from which a sample can be selected.

Natural differences between the results obtained from different samples selected from the same population.

Information consisting of two side lengths and the included angle between them.

A number that multiplies a vector, changing its length and, if negative, reversing its direction.

The relationship between lengths on a drawing and the corresponding actual lengths or lengths in another drawing.

A representation in which every length is enlarged or reduced by the same scale factor.

A number used in an enlargement whose magnitude multiplies corresponding side lengths; a negative sign places image points on the opposite side of the centre.