To determine the pitches of a triad, you can use a system similar to the stepwise approach given for figuring out the pitches of major and minor scales. Each of these triads consists of scale degrees 1, 3, and 5 of a diatonic scale.
Follow these steps to determine the pitches of a major triad.
1. Write out the scale degrees under the staff. Since a triad consists of scale degrees 1, 3, and 5, it is only necessary to write the numbers 1 through 5. B flat major will serve as our example.
2. Write the pattern of whole steps and half steps as they occur between each scale degree (W W H W).
3. Write in the first five pitches of that diatonic scale. Do not skip any pitches or repeat any pitches.
4. Check every whole step and half step in the scale and write in the accidentals, when appropriate. If you need help remembering half steps and whole steps, reread that section of the website.
Scale degree 1 to 2 is a whole step. A whole step above B flat is C, so no accidental is needed.
Scale degree 2 to 3 is a whole step. A whole step above C is D, so no accidental is needed.
Scale degree 3 to 4 is a half step. A half step above D is E flat, so you need to write a flat in front of the E.
Scale degree 4 to 5 is a whole step. A whole step above E flat is F.
The triad consist of scale degrees 1, 3, and 5 played at the same time. Therefore, the notes of a B flat major triad are B flat, D, and F. When these notes are played one at a time, they are called a B flat major arpeggio.