[Updated August 17 with my Excel solution and a link to the thread with a wide variety of solution techniques.]
Here’s a geometry puzzle for your weekend. The four squares are the same size. The arc is 1/4 of a true circle. You have everything you need to solve this.
The original post was on Twitter from Catriona Agg (@Cshearer41). She has a library of puzzles like this. Here’s the tweet:
If you solve this, please post your solution in the comments. Show your work. Use the following labels for various points on the diagram. If you add points, label them and make it clear what you’ve done.