Polygons Examples

Which of the following shapes is not a polygon?

a)

b)

c)

d)

Image c is not a polygon. Even though it has more than 3 sides, it is not closed. There is a gap between two of the sides so it is not a polygon.

Image b is a polygon, even though it doesn't look like most of the polygons we work with. It has three or more sides and each of the sides meet, which means it's closed. This makes it a polygon.

Identify the type of polygon shown below. Then name all of the shape's sides and vertices.

This polygon has 5 sides so it is a pentagon.

The sides of the pentagon are:
AB, BC, CD, DE, and EA.

The vertices of the polygon are:
A, B, C, D, and E.

Label each polygon as either equiangular, equilateral, or regular.

a)

b)

c)

d)

Shape a) is a square and, by definition, has the same side lengths, and equal angles with each angle equal to 90°. A square is a regular polygon.

Shape b) is a rhombus. All four sides are the same length, but two angles are acute and two are obtuse, so the angles are not all equal. This shape is equilateral.

Shape c) is a rectangle so all four angles are equal, but the sides are not the same length. This rectangle is equiangular.

Shape d) is an equilateral and equiangular triangle so it is a regular polygon.

Label each shape as convex or concave.

a)

b)

c)

d)

a) concave

b) convex

c) concave

d) concave