Maths & numbers
Triangle centres from coordinates
Plot the centroid, incentre, circumcentre, orthocentre and nine-point centre.
A clear answer. Here’s how.
Requires exactly three non-collinear two-dimensional vertices. Uses side-length barycentric weights for the incentre, perpendicular-bisector equations for the circumcentre, the vector identity H=A+B+C−2O for the orthocentre, and (O+H)/2 for the nine-point centre. Reports area, inradius and circumradius. Degenerate or extremely narrow triangles are rejected at a scale-relative tolerance.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Point CSV
X,Y 0,0 4,0 0,3
Example result
| Centre | X | Y |
|---|---|---|
| Centroid | 1.33333333333 | 1 |
| Incentre | 1 | 1 |
| Circumcentre | 2 | 1.5 |
| Orthocentre | 0 | 0 |
| Nine-point centre | 1 | 0.75 |
Triangle area 6; inradius 1; circumradius 2.5. All coordinates use the input unit.