# Equation of a Shape The **equation** of a shape drawn on a set of axes is an equation that is satisfied by the points of the shape and no others. ## Equation of a Straight Line A straight line in the $x{-}y$-plane can be described by an equation of the form: \[ a x + b y = c \] If $b \ne 0$, this can be rearranged to the form: \[ y = m x + c \] [[!redirects equation of a line]] [[!redirects equations of lines]] [[!redirects equation of a straight line]]