Area of an Inscribed Triangle in Terms of the Product of Its Sides
The area of a triangle inscribed in a circle of diameter 1 can be expressed in terms of the product of its three sides. This Demonstration presents a step-by-step derivation of this result.
This is one of many interesting results concerning triangles. An impressive list appears in .
A detailed step-by-step derivation for this particular case may be useful for geometry amateurs, and the source code provides some tips for geometric drawing with the Wolfram Language.
 A. Bogomolny. "Metric Relations in a Triangle." (Oct 8, 2019) www.cut-the-knot.org/triangle/MetricRelationsInTriangle.shtml.