1. Polygons
By Beth Roberts

2. Polygons
A polygon is a figure that is made up of only line segments. It is a closed figure and its sides intersect in exactly two places.
There are many different polygons; this slide will look at the triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, nonagon and decagon.
There are regular polygons and irregular polygons.

3. Regular Polygons
A regular polygon is a polygon where all sides are equal in length and all angles have the same measure.
An equilateral triangle is a regular polygon and so is a square.

4. Irregular Polygons
In an irregular polygon, one or more sides do not equal the length of the others.

5. Triangles A triangle is the simplest polygon.
Triangles only have three sides.
There are several different types of triangles.
The sum of the angle measures in a triangle is 180 degrees.

6. Triangles (continued)
Triangles classified by their sides are the isosceles, scalene and equilateral.
Triangles classified by their angle measure are the acute, obtuse and right.

7. Triangles (continued)
Triangle Image

8. Quadrilaterals A quadrilateral is a four-sided polygon.
The sum of the angle measures in a quadrilateral is 360 degrees.
There are several different types of quadrilaterals.

9. Types of Quadrilaterals
Rectangle – any quadrilateral where all four angles are right angles.
Square - a quadrilateral with four equal sides that meet at 90 degree angles.
Parallelogram - a quadrilateral with two sets of parallel sides.

10. Types of Quadrilaterals (continued)
Rhombus - a quadrilateral where all four sides are of equal length. The difference between a square and a rhombus is that in a rhombus, all the sides don't need to meet at 90 degree angles.
Trapezoid - a quadrilateral that has exactly one pair of parallel sides.

11. Images of Quadrilaterals

12. Pentagon A pentagon is a five-sided polygon.
The sum of the angles in a pentagon is 540 degrees.

13. Hexagon A hexagon is a six-sided polygon.
The sum of the angles in a hexagon is 720 degrees.

14. Heptagon A heptagon is a seven-sided polygon.
The sum of the angle measures in a heptagon is 900 degrees.

15. Octagon An octagon is an eight-sided figure.
The sum of the angle measures in an octagon is 1080 degrees.

16. Nonagon A nonagon is a nine-sided figure.
The sum of the angle measures in a nonagon is 1260 degrees.

17. Decagon A decagon is a ten-sided figure.
The sum of the angle measures in a decagon is 1440 degrees.

18. Links to Web Pages for More Information on Polygons
Figures and Polygons
Polygons
How Many Sides?
What is a Polygon?

19. Further Information Polygon Worksheet Worksheet Answers
Back to Polygon Information