Chord building grid
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A chord building grid is a graphic reference for determining which notes are included in a particular chord. Different geometric shapes on the chart form different types of chords. For example, notes forming an upward-pointing triangle make a major chord, while an inverted triangle forms a minor chord. Using this reference you can see an F♯ minor chord contains F♯, A and C♯, and an A major chord contains A, C♯ and E.
Here are a few patterns for chords—major, minor, major seventh, suspended fourth and diminished. In each shape, the circled position indicates the root. Other chords can be built using the scale relationships given in the center cluster of notes. (The "R" in the cluster indicates the root position.) The numbers indicate different harmonies based on the major scale; 3 means a major third, b3 (a "flat third") is a minor third. For any given note, the note to the right forms a minor third harmony, and the note down and to the left forms a major third harmony. In a similar fashion, the note down and to the right forms a perfect fifth, and so on.