Endpoint Calculator – From Midpoint
Find the missing endpoint of a plane segment from one endpoint and its midpoint.
Formula
xB = 2xM − xA; yB = 2yM − yA
xB ≈ 2×(3)-(1) · yB ≈ 2×(4)-(2)
How to use
- Enter the known endpoint A.
- Enter midpoint M in the same coordinate system.
- Read the missing endpoint B.
Examples
- A=(1;2), M=(3;4) → B=(5;6).
Frequently asked questions
Which point is the midpoint?
M lies halfway between A and B.
May coordinates be negative?
Yes. All coordinates can be positive, negative or zero.
Does this work for a ray?
No. It solves a finite segment with a specified midpoint.
Sources
Updated: