https://math.stackexchange.com/questions/5133803/determining-a-quadrilateral-up-to-similarity-with-four-angles
geometry - Determining a quadrilateral up to similarity with four angles - Mathematics Stack...
A triangle, up to similarity, is completely determined by two of its internal angles. A quadrilateral can be divided into two triangles, and those two...
geometryquadrilateralsimilarityfourangles