In this introduction, figuration of a triad or chord is understood to be the assignment of its numerical value and position in the key, including the representation of the intervals in the chord.
In a previous discussion you would have learnt that chords may be written in root position, first inversion and second inversion. Here, we are concerned in how to figure the chord using a meaningful and broadly accepted method.
When the entire scales is harmonised as in the example below, we find that some triads are major and some are minor. Chords 1, 4, 5 and 8 are major in every major key, while chords 2, 3, and 6 are minor. The triad formed on the 7th note is know as a half diminished.
If we figure the triads below it does not make sense to use regular numbers, e.g.
C D E F G A B C
1 2 3 4 5 6 7 8
These numbers do not tell us whether a triad i major or minor. Roman numerals are an ideal way to represent which triads are minor and major. Use lowercase Roman numerals for minor and diminished chords and uppercase Roman numerals for major and augmented chords chords.
Using Roman Numerals in Figuration of Triads
Lowercase = minor while uppercase = major C D E F G A B C I ii III IV V vi vii VIII M m m M M mi dim M
Uppercase M is used for Major triads, wile lowercase m, is used to name the minor triad in the table.
Some of the conventions used in figuration are numbers and alphabets. They are used to indicate the position of the chord, such as root position, first inversion and second inversion.
The alphabet, a, is used to represent a triad in root position. Example: Ia, means that the tonic triad C major, is in root position. The, a, designation is not witten as the absense of any designation such as a,b or c, suggests that the triad is in root position. We, therefore, do not write the 'a' designation for a triad in root position.
The alphabet, b, is used to indicate a first inversion triad. Example: Ib, means that the tonic triad C major is written in the first inversion.
The alphabet, c, is used to indicate a second inversion triad Example: Ic, means that the tonic triad C major is written in the second inversion.