Co-ordinate Geometry (Algebra 3)

Gradient

The steepness and direction of a line when read from left to right. Also called slope.

Rate of change

How fast a graph's y-variable changes compared to its x-variable.

Undefined

A line has a slope that is considered undefined when it does not have any horizontal value (vertical line).

y-intercept

The point or points where the line or curve crosses the y-axis.

x-intercept

The point or points where the line or curve crosses the x-axis.

Co-ordinate

A pair of numbers (x, y) that locate a point on a plane.

Origin

The point (0, 0) where the axes cross.

Cartesian (plane)

The flat surface defined by the x-axis and y-axis.

Axis / Axes

The horizontal (x) and vertical (y) number lines.

Plot

To mark a point on a graph using its coordinates.

Horizontal

Parallel to the x-axis (left-right).

Vertical

Parallel to the y-axis (up-down).

Graph

A diagram showing the relation between variable quantities.