Incentro do Triângulo
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
incentro
About this calculator
The Triangle Incenter Calculator determines the coordinates of the incenter, which is the intersection point of the internal angle bisectors of a triangle. The incenter is the center of the inscribed circle (incircle) that touches all three sides. The calculation uses the formula I = (a·A + b·B + c·C)/(a+b+c), where a, b, c are the lengths of the sides opposite vertices A, B, C respectively, and A, B, C are the vertex coordinates. This tool is helpful for geometry students and professionals who need to quickly find the incenter without manual calculations.
Usage is straightforward: the user inputs the coordinates of the three vertices (x, y) and the lengths of the opposite sides. The calculator applies the weighted coordinate formula, where weights are the side lengths. The result is a point (x, y) representing the incenter. It is crucial that the side lengths correspond correctly to the opposite vertices: side a opposite vertex A, b opposite B, and c opposite C. Otherwise, the result will be incorrect.
This calculator is especially useful in geometry problems involving incircles, such as finding the incircle radius (distance from incenter to any side) or in geometric constructions. It is also applied in engineering and architecture projects requiring precise placement of circular elements inside triangles. Note that the incenter exists only for non-degenerate triangles (non-zero area).
Cautions: ensure vertex coordinates and side lengths are correct and consistent. Side lengths must be positive. The incenter is always inside the triangle, so the result should lie within the triangular region. If the calculated point is outside, review the input data.
Frequently asked questions
What is the incenter of a triangle?
The incenter is the intersection point of the three internal angle bisectors. It is the center of the incircle, which touches all sides of the triangle.
How does the calculator find the incenter?
It uses the formula I = (a·A + b·B + c·C)/(a+b+c), where a, b, c are the lengths of the sides opposite vertices A, B, C respectively, and A, B, C are the vertex coordinates.
Do I need to enter side lengths or vertex coordinates?
You need both: the (x, y) coordinates of each vertex and the lengths of the sides opposite each vertex.
What if the result is outside the triangle?
Check that the side lengths and coordinates are entered correctly and correspond to the opposite vertices. The incenter is always inside the triangle.
Does this calculator work for any triangle?
Yes, for any non-degenerate triangle (area greater than zero). Degenerate triangles (collinear points) do not have an incenter.