How to calculate the area of an octagon
There area two main methods to calculate the area of an octagon.
If you know the length of “H” as well as “B” the length of one of the 8 sides, then you can use this method.
The octagon is made up of 8 triangles, so find the area of one triangle and multiply by 8.
The total height “A” of the octagon is 16.9m and the length of a side “B” is 7m, calculate the area. A = 16.9mB = 7m First calculate the area of one triangle Area of a triangle = 0.5 x Base x Height The height of one triangle = A ÷ 2 = 16.9 ÷ 2 = 8.45Area of a triangle = 0.5 x Base x HeightArea of a triangle = 0.5 x 7m x 8.45 = 29.575m2There are 8 triangles in an octagon, so 29.575m2 x 8 = 236.6m2Answer = 236.6m2
You can use method two if you only know the length of one of the 8 sides.
The length of one of the 8 sides “B” is 7m, calculate the area of the octagon. B = 7mThe area of an octagon = 2 x (1 + √2) x B2Area = 2 x (1 + 1.414213562) x 72Area = 2 x (1 + 1.414213562) x 49Area = 2 x (2.414213562) x 49Area = 4.828427124 x 49The area of an octagon = 236.6m2