- a dot P(x1, y1)
- a straight line r: ax + by + c = 0
The distance between them (dpr) is given by:
Let's calculate the distance, for example, from the point P(-1.2) straight r: x - 2y + 1 = 0.
We have P(-1, 2) = P(x1, y1), a = 1, b = - 2 and c = 1. Like this: