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Formula for the area of a octagon?

Updated: 4/28/2022
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11y ago

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The interior angles of an octagon are 135 degrees, which means that if you extend one of the sides, the complementary external angle is 45 degrees. So imagine an octagon instead as a square with four cut out right triangles on the corners.

Let's start with the length of a side x. Since the right triangles have a hypotenuse x, we know that the legs are length (sqrt(2)/2)x. The area of the triangle is 1/2 * base * height, which means one triangle is x2 / 4. Since there are 4 triangles, the total area of the triangles is x2.

Next, we need the area of the square. One side is a leg of the octagon plus two legs of our triangles, which would be x + (sqrt(2)/2)x + (sqrt(2)/2)x = x + sqrt(2)*x. Square this, and you get 3x2 + 2*sqrt(2)*x2. But! Subtract the area of the triangles from this, and you get (after some redistributing):

A = 2x2 * (1 + sqrt(2))

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Q: Formula for the area of a octagon?
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How does the formula of a octagon work?

There is insufficient information for us to answer this question. Please edit the question to include more context or relevant information. What formula of an octagon are you referring to: the sum of the interior angles, the frustum of a regular octagon, the area, the perimeter, the number of diagonals? The possibilities are almost endless!


What is the formula to find the area of an octagon?

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What is the formula find the area of an octagon?

one way to do it is to first draw a rectangle around the octagon then multiply length by width then subtract the area of the four triangles out side the octagon from your total answer. OR You can use the formula A= 2 s2 cot(π/h) π is supposed to be pi s2 is supposed to be s squared Cot is an abbreviation for cotangent


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A regular octagon with sides of length 7 and an apothem of length 8.45 has an area of how many square units?

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