Point slope form formula is used to find the equation of a straight line. Equation of a straight line calculated using various different methods. Point Slope form is one such method which uses slope to find the equation. It is given as (y - y1) = m(x- x1). Here x1 and y1 is the known point, whereas 'm' is the slope of the line. Here, the difference between (y-y1) in a y coordinate plane is proportional to the difference between (x-x1) in a x coordinate plane.