Primary triad

In

music, as opposed to an auxiliary triad or secondary triad.

Each triad found in a diatonic key corresponds to a particular

, whose roots begin on the second, third, sixth, and seventh degrees (respectively) of the diatonic scale, otherwise symbolized: ii, iii, vi, and vii^o (again, respectively). They function as auxiliary or supportive triads to the primary triads.

In C major these are:

• I C
• V G
• IV F
• vi Am
• iii Em
• ii Dm
• vii^o Bdim

In a

harmony.

Auxiliary chords may be considered parallel and contrast chords derived from the primary triads. For example, the supertonic, ii, is the subdominant parallel, relative of IV (in C: a d minor chord is the subdominant parallel, the subdominant is an F major chord). Being a parallel chord in a major key it is derived through raising the fifth a major second (C of F–A–C rises to D → F–A–D, an inversion of D–F–A). Alternatively, secondary triads may be considered ii, iii, and vi.^[3] In C major these are:^[3]

• ii Dm
• iii Em
• vi Am

In A minor these are:^[3]

• ii^o Bdim
• III C
• VI F

See also

• Subsidiary chord

References