A major key major triad can be built on the first, fourth, and fifth scale degrees of the major scale.
For example, in the C major scale:
- The I chord (C major triad) is built on the 1st degree (C).
- The IV chord (F major triad) is built on the 4th degree (F).
- The V chord (G major triad) is built on the 5th degree (G).
These triads form the primary chords in a major key and are fundamental to Western music harmony.