I am looking for an open source program where I can draw lines, designate parallel constraints, define distances, etc. and then at the end, I can ask "what is this area [between 4 points] in terms of these distances?", and it will give me a formula something like D1 * (D2 + D3) - D4 * D5. I would very much prefer to be able to see the constructions graphically. If I can also edit the constructions graphically (point and click) rather than learn some kind of geometry programming language, that would be ideal but not essential.
I tried using GeoGebra but couldn't find a way for it to tell me a formula.
I am using Ubuntu operating system.