A-Level Maths Edexcel (9MA0)

Understand and use the equation of a straight line, including the forms
$y - y_1 = m(x - x_1)$ and
$ax + by + c = 0$.

To include the equation of a line through two given points, and the equation of a line parallel (or perpendicular) to a given line through a given point.

Gradient conditions for two straight lines to be parallel or perpendicular.

$m' = m$ for parallel lines and $m' = -\frac{1}{m}$ for perpendicular lines.

Be able to use straight line models in a variety of contexts.

For example, the line for converting degrees Celsius to degrees Fahrenheit, distance against time for constant speed, etc.