My conclution is that the sum of the 4 angles of each quadrilateral is of 360°. The angle of the sum of all the angles of a quadrilateral is of 180° more than the angle of sum of the 3 angles of a triangle.
centers of Triangles
MTK GeoGebra Tools
10.2.1a #941955 Correct Answer2
[Quantum Continuum]: Lemma - All Primes - Root rn Order - [graphical method]
Sim12: Sum of Interior Angles of a Quadrilateral
Telling time from clocks