Hi all! I develop an application in computer science that shows the execution of an Algorithm that triangulates a simple polygon. The first thing I have to do is to transform the given Polygon into monotone pieces, in order to do that I have to figure out the interior angles of the simple polygon. I just know the coordinates of the vertices of my polygon. Now my problem is how I should calculate the interior angle between two edges. And with interior I mean interior of the polygon. Two edges form a triangle which allows me to calculate angles easily but how do I know if I should calculate the exterior or the interior angle of that specific triangle. Is the interior angle of the triangle inside the polygon or the external angle? Thanks in advance for any answers!!