u/Accurate-Click1363

Take two squares ABED and FBCG such that A, B and C are collinear, and D, E, F, and G are on the same side of line AC. AB=a, and BC=b.

Using just a straightedge, construct a square whose side has a length of sqrt(a2+b2). 

I posted the same puzzle on Puzzling SE two months ago, link will be added after it is solved.

Edit: It’s been solved, so here’s the link:

https://puzzling.stackexchange.com/questions/137953/straightedge-only-construction