Convex polygon : Polygon such that every 2 points within it can be joined by a segment that does not intersect the boundaries of the polygon. A triangle is a convex polygon.

Simple polygon : a region enclosed by a single closed polygonal chain that does not intersect itself. There are no holes in simple polygons.

Two Ears Theorem : Every simple polygon has 2 ears.

Polygon Ears : We say there is an ear at vertex V in P if the triangle formed by v and its 2 adjacent vertices is inside P and there is no vertice of P inside this triangle.

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