The_Complete_Idiot%27s_Guide_To_Music_Theory

There are many different ways to indicate a diminished chord, as shown in the
following table:
Notation for Diminished Chords
Diminished Chord Notation Example
diminished C diminished
dimin C dimin
dim C dim
º Cº
While it’s important to learn about diminished and augmented chords, you won’t
run into too many of them, especially in popular music. If you base the root of
your chord on the notes of a major scale, as you’ll learn in Chapter 10, only
the seventh degree triad forms a diminished chord. (Triads based on the other
degrees of the scale form major or minor chords.) There is no augmented chord
found on any degree of the major scale.
Augmented Chords
Note
An augmented chord is like a major chord with a raised fifth; thus an augmented
chord consists of a root, a major third, and an augmented (raised) fifth. This is
sometimes notated 1-3-♯5.
For example, the C augmented chord includes the notes C, E, and G♯.
Here’s a quick look at how to build augmented chords on every note of the
scale:
Augmented triads.
There are many different ways to indicate an augmented chord, as shown in the
following table:
Notation for Augmented Chords
Augmented Chord Notation Example
augmented C augmented
aug C aug
+ C+
Chapter 9: Chords 115
Note
Did you spot the double
sharp on the fifth of the B
augmented chord in the
illustration of augmented
chords?