Side A in meters
Side B in meters
Side C in meters
Calculate

This tool is based on the idea that all areas need to be divided into triagles. js example found here https://www.programiz.com/javascript/examples/area-triangle

Reson for this is that a triangle with known sides can only have one shape. The angles will always be the same. On the other hand, an area with more sides than 3 the shape can differ a lot depending on the angles of the corners.

Imagine a perfect square compared with a recatngle with the same sides but squashed almost so it is flat. If that rectangle is defined by 2 triangles the shape will allways be only one exacly defined version.

Imagine a component where you have some standard way of give the length of each of the side in a triangle and it spits out the area.