The Wolfram Language provides fully integrated support for plane geometry, including basic regions such as points, lines, triangles, and disks; functions for computing basic properties such as arc length and area; and nearest points to solvers to find the intersection of regions or integrals over regions.
SSSTriangle — triangle specified by the length of its sides
TriangleConstruct — incircle, circumcircle, altitude, ... of triangles
TriangleCenter — orthocenter, circumcenter, incenter, ... of triangles
Graphics — visualize regions with different styles
TriangleMeasurement — circumradius, height, ... of triangles
RegionMember — test whether a point is in a region
RegionNearest — nearest point in a region to a given point
GeometricScene — symbolic representation of a geometric scene
RandomInstance — find and display a random instance of a geometric scene
FindGeometricConjectures — find conjectures about a geometric scene
GeometricAssertion — assert geometric properties or relations (convex, parallel, congruent, ...)
FindInstance — find examples of points in a region
Solve — find curve crossings etc.