What is the name of a triad built from root, minor third, and diminished fifth?

• A. Augmented Triad
• B. Major Triad
• C. Diminished Triad
• D. Minor Triad

Answer: (C)

Triad quality is determined by the intervals from the root to the third and to the fifth. If the third is minor and the fifth is diminished, you get a diminished triad. The diminished fifth means the fifth degree is lowered a half step from a perfect fifth, giving that tense, dark sound. For example, a C diminished triad is C–Eb–Gb: C to Eb is a minor third, and C to Gb is a diminished fifth. This differs from a major triad (major third and perfect fifth), a minor triad (minor third and perfect fifth), or an augmented triad (major third and augmented fifth).