Coordinate Geometry
Cartesian coordinate
$(x,y)$
Gradient
$m=\dfrac{y_1-y_2}{x_1-x_2}$
Equation
$y-y_1=m(x-x_1)$
$y=mx+c$
*Vertical line: $x=a$
*Horizontal line: $y=b$
$y=mx+c$
*Vertical line: $x=a$
*Horizontal line: $y=b$
Length
$\text{Length } = \sqrt{(x_2 – x_1)^2 + (y_2 – y_1)^2}$
