You can also classify a polygon as concave or convex, using the diagonals of the polygon. A diagonal is a segment that connects two nonconsecutive vertices.

A convex polygon has no diagonal with points outside the polygon.

A concave polygon has at least one diagonal with points outside the polygon.

In this textbook, a polygon is convex unless otherwise stated.

Example 2

Classify the polygon by its number of sides. Tell whether the polygon is convex or concave.

The polygon has six sides. Therefore, it is a hexagon.

No diagonal of the hexagon contains points outside the hexagon. The hexagon is convex.

Exercises

Is the figure a polygon? If not, explain why.

Name the polygon. Then identify its sides and angles.

Classify the polygon by its number of sides. Tell whether the polygon is convex or concave.

Table of Contents