Which triad types contain a perfect fifth between the root and the fifth?
There are two main triad types (chords) that contain a perfect
fifth between the root and the fifth: the major chord and the minor
chord.
The major chord is created by starting with a note (the root),
adding a major third on top of that, and adding a minor third on
top of that note. A C major chord would look like this: C, E, G
(with the E and the G stacked on top of the C).
The minor chord is created by starting with a note (again, the
root), adding a minor third, and then adding a major third--just
the opposite of a major chord. A C minor chord would look like
this: C, Eb (E-flat), G.