Perimeter and area of regular polygons

Learn how to calculate the area and the perimeter of a regular polygon.

Notes

Learn what the apothem of a regular polygon is. It's very important if you want to find the area of a regular polygon.

Learn how to calculate the perimeter of a regular polygon.

Table of contents of this lesson: Perimeter and area of regular polygons

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Apothem of regular polygons

Apothem of pentagon

Fixed numbers table

 

If you want to find the area of regular polygons, you will need a new element: the apothem.

Regular polygons have equal sides and angles. If you connect the vertexes of the sides to the centre of the polygon, you will have as many equal isosceles triangles as the sides of the polygon.

The apothem is the line connecting the centre of the polygon to the midpoint of one of the polygon's sides. So, the apothem is the height of every little triangle. There is a connection between the apothem and the polygon's side: the fixed number.

When you divide the apothem of a square by the length of its side, the result is always 0,5!

Area of regular polygons

Area of regular polygons

Perimeter of regular polygons

Perimeter of regular polygons