  
Introduction
In Lessons 7 and 8 we learned to write and analyze
isolated triads. In this lesson we will explore how these chords
relate to each other and function within a key.
1
Primary
triads
The three most important chords are the primary
triads. They are constructed above
the first, fourth, and fifth pitches of the major or minor scale.
In a diatonic major key, they are the three major triads and have
a particularly close harmonic relationship. The dominant (V) lies
a perfect fifth above the tonic, and the subdominant (IV) lies a
perfect fifth below the tonic.
The tonic triad (I), constructed
on the first scale degree, is first in importance. Tonal musical
compositions often begin and almost invariably end on the tonic.
The dominant triad has strong
harmonic influence. Because it contains the leading tone, it often
precedes the tonic triad. The subdominant triad is the third most
important chord. Following are the primary triads in the key of
F major:

In a minor key, the harmonic form of the scale (raised
7th scale degree) is used. Therefore, the dominant triad is major.
Following are the primary triads in the key of f minor:




  
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