In one of his notebooks, Euclid gave a complex procedure for solving the following problem. With computers, perhaps there is an easier way.
In a 2D plane, consider a line segment AB, another point C which is not collinear with AB, and a triangle DEF. The goal is to find points G and H such that:
• H is on the ray AC (it may be closer to A than C or further away, but angle CAB is the same as angle HAB)
• ABGH is a parallelogram (AB is parallel to GH, AH is parallel to BG)
• The area of parallelogram ABGH is the same as the area of triangle DEF