mathlib

6959abed - feat(geometry/euclidean/angle/oriented/affine): more collinearity / affine independence lemmas (#17815)

feat(geometry/euclidean/angle/oriented/affine): more collinearity / affine independence lemmas (#17815) Add lemmas that, if twice the oriented angles between two triples of points are equal, one triple is affinely independent / collinear if and only if the other triple is.