Directed Line Segment Ratio Calculator

Find division point on directed line segment. If P divides AB in ratio m:n, then P = (n×A + m×B) / (m+n).

Formula

P = (n·A + m·B) / (m+n); divides segment AB in ratio m:n
  • Section formula for internal division
  • P = (n·x₁ + m·x₂)/(m+n), (n·y₁ + m·y₂)/(m+n)
  • For external division: use P = (n·A - m·B) / (n-m)
  • Directed segment: sign of distances shows direction

Example

Inputs
  • Point A x-coordinate: 1
  • Point A y-coordinate: 2
  • Point B x-coordinate: 5
  • Point B y-coordinate: 8
  • Ratio m (part 1): 1
  • Ratio n (part 2): 2

A(1,2), B(5,8), ratio 1:2: P = (2·1+1·5)/(1+2), (2·2+1·8)/(1+2) = (7/3, 4)

Frequently asked questions

What's the section formula?
Point dividing segment in ratio m:n: P = (n·A + m·B)/(m+n)
What's the difference between internal and external division?
Internal: P between A,B (ratio m:n). External: P outside (ratio -m:n or m:-n).