And muliplying that by 10, the number of triangles in the dome floor, I get an area of 29,389.26 square units. Now, multiplying the altitude by half the base length, we get a triangle area of 2,938.926. The area of an isosceles triangle is half the base length times the altitude.

Each will have the following edge lengths: 100, 100 and 61.803399 (edge B is the base of the triangle). To derive the coefficient, divide the floor into 10 identical isosceles triangles. Or, using a more precise coefficient, namely 2.938926, I get an area of 29,389.26 square units, The formula should be 2.94 x R squared, which gives a floor area of 29,400 square units. So your calculator is using the following formula (or equivalent): Floor area = 3.09 x R squared, where R is the radius. Hmmm.If I enter a dome radius of 100 units, your calculator gives a floor area of 30,900 sq. I uploaded this image of the strut labels:

Use this tool to find out the total snow load on any size geodesic dome. Use this tool to find out the total wind load on any size geodesic dome. Use this tool to find out the strut lengths and panel sizes to build a trapezium panel dome. Use this tool to find out the strut lengths and panel sizes to build a four frequency geodesic dome. Use this tool to find out the strut lengths and panel sizes to build a three frequency geodesic dome. Use this tool to find out the strut lengths and panel sizes to build a two frequency geodesic dome. Use this tool to find out floor area, diameter, surface area, circumference and volume of a dome. Below are links to various dome tools for calculating strut lengths, floor area, panel sizes and other useful measurments for building geodesic, segmented and other types of dome.

Geodesic Dome Calculator