I noticed while working on the basic idea worksheet that some of the harmonic patterns in appendix A contain sharp and flat chords (such as VI♯ and iv♭). How are these chords built?
The capital and lowercase denote major and minor, so the first chord is a Major VI chord. The reason there is a sharp, is because a major VI chord is not a part of the key and so you must chromatically raise the 3rd. For instance, in C major, the major VI# chord would be A major, which has a C#.
The iv♭ is the same concept. In C major, it would be an F minor with a flat 3rd.
Thanks, that makes sense