What is the difference between convex and concave polyhedron

 

 The difference between convex and concave polygons lies in the measures of their angles. For a polygon to be convex, all of its interior angles must be less than 180 degrees. Otherwise, the polygon is concave. Another way to think of it is this: the diagonals of a convex polygon will all be in the interior of the polygon, whereas certain diagonals of a concave polygon will lie outside the polygon, on its exterior. Below in Part A are some convex polygons, and in Part B, some concave polygons. In the rest of this text, you can assume that every polygon discussed is convex.