A convex polygon is a polygon in which no line that contains a side of the polygon contains points in the interior of the polygon. Alternatively, a polygon is convex if all the interior angles measure less than $180^{\circ }.$ Note that all triangles are convex polygons. There are some characteristics that can be listed about convex polygons.

• All the vertices of the polygon point outwards.
• All the diagonals lie inside the polygon.
• The segment joining any two interior points of the polygon is fully contained in the polygon.

When a polygon is not convex, it is said to be concave.