Mathematics key terms

A quantity with both a size and a direction; in two dimensions, it can describe horizontal and vertical movement.

A solid object with length, width and height.

The distance of a number from zero. For example, $|-7|=7$.

The change in velocity per unit of time, commonly measured in metres per second squared.

The size of the place value to which a number has been rounded or truncated, such as $1$, $0.1$ or $100$.

An angle greater than 0° but less than 90°.

Sides or angles next to one another and sharing a vertex or side.

Angles next to one another that share a vertex and one side, without overlapping.

The side next to the acute angle being considered in a right-angled triangle, excluding the hypotenuse.

A connected sequence of mathematical statements used to justify a conclusion.

A mathematical statement made from numbers, letters and operations, without an equals sign; for example, $5n+2$.

An algebraic expression written as one expression divided by another, with a denominator that must not equal zero.

A mathematical representation of a real situation, relationship or procedure.

An algebraic argument that establishes that a claim must be true in every case covered by it.

Angles at different intersections on opposite sides of a transversal, either both between the two lines or both outside them. They are equal when those lines are parallel.

The rule that the angle between a tangent and a chord equals the angle subtended by that chord in the opposite segment of the circle.

The situation in which given side–side–angle information can produce two different valid triangles because $\sin\theta=\sin(180^\circ-\theta)$.

The greatest vertical distance between the centre line and a maximum or minimum of a repeating graph.

The angle that measures how far one direction turns from another, measured in degrees (°).

The angle formed by the line segments $BA$ and $BC$, with its vertex at the middle letter $B$.

An angle formed at the centre of a circle by two radii.

An angle whose vertex lies on the circumference and whose arms meet the circumference at two other points.

The acute angle between a line and its perpendicular projection onto a plane.

A line or ray that divides an angle into two equal angles; points on it are equally far from the angle’s sides.

A known angle and the side directly opposite it in a triangle.

Two angles next to each other whose outer arms form a straight line; together they measure 180°.

An angle formed by lines from a point on the circumference to the two endpoints of an arc or chord.

An angle formed by joining a point to both endpoints of an arc.

The direction opposite to the movement of the hands of a clock.

The vertex of a cone or pyramid opposite its base.