You will need

- - the range;
- calculator.

Instruction

1

To find the area of an arbitrary

**octagon**, click within arbitrary point and swipe from her segments to each vertex. Then measure the lengths of the sides of each of the eight resulting triangles. Then, using the Heron formula, calculate the area of each triangle. And finally, add the area of all triangles. The resulting amount will be the area**of the octagon**.2

To use the Heron formula, calculate first properiter triangle:p = (a + b + c) / 2 where a, b, c the lengths of the sides of the triangle; p – marking of properiety.Considering properiter triangle, substitute the value obtained into the formula:S = √(p*(p-a)*(p-b)*(p-c)), where S is the area of a triangle.

3

If the octagon convex (no interior angles 180º large), the interior-point select any of the vertices

**of the octagon**. In this case, you get a total of six triangles, which is a bit easier finding the area**of an octagon**. The method of calculation of areas of triangles is the same as described in the previous paragraph.4

If an octagon has equal sides and angles, then this is the right geometrical shape – the octagon. To calculate the area of this

**octagon**, use the formula:S = 2 * k * a2, where a is the length of sides of a regular**octagon**; k – coefficient equal to (1+√2)≈2,4142135623731.5

In the solution of school problems sometimes is given the length of sides of a regular

**octagon**, and the length of its largest and smallest diagonals. In this case, use the formula:S = d * D, where d is the length of the smaller diagonal; D is the length of the major diagonal.Larger diagonal of the octagon is a segment that connects two opposite vertices. Lower right diagonal**of the octagon**bude segment connecting the two vertices through one.