How to calculate the area of ​​an object?

Question

Geometry

Help me understand how to solve a working problem:
I have rectangles (can be arbitrary), for which I know the width, height and X / Y of the upper left point. In these rectangles, the program enters a rectangle (that is, everything will be filled) or ellipses (with equal height and width a circle) or a triangle. I understand how to find the area of ​​each of the figures, but how to find the total area that excludes the overlap of sides (i.e. if the faces were superimposed one on one, take into account only one)?
So far, the only option that I have come up with is to create an array of 1 in 1 size to real elements, which, as it were, will digitize each of the objects. But in this version, I can’t understand how to correctly find curving points, for example, that go around a circle.
Has anyone faced a similar issue? What can you advise?