In Harold Jacobs Geometry we skipped over material is chapters 12, 13, 15, and 16 because
1. It is not needed for ACT/SAT nor future math classes, and
2. it is a overly complex for the course at this level.
Our recommendation is that the student look over this material and get the idea – but move on. You will find a test problem that points back to some of this material in a trivial way, but we decided to leave it in as a learning tool since often in life we find ourselves having to dig a little to get to an answer – even when being tested. Since we recommend open book tests, this usually works well. And, just in case, it is only one problem and the teacher can decide to skip it if they like.