I was introduced to Euclidean geometry through a workbook for middle/high schoolers that introduced a beginning proof and through its solution, introduced another (more advanced) proof. I’m having an incredible time trying to find that book and/or something comparable. Does anyone here have something along this vein they could recommend?
Eternally grateful!
Try EGMO and UKMT books, as I have used them and like them a lot. Also, try the 106,107 and 110 series from Titu for alternatives (with increasing difficulty, all has a solution manual). If you want one with less Olympiad Mathematics flavor, try Coexter. Free sources include this and this (the latter is a university course note).