Diminished triad

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In music theory, a diminished triad is a triad with a minor third and a diminished fifth above the root. When using chord symbols, it may be indicated by the symbols "dim", "o", "m♭5", or "MI(♭5)". However, in most popular-music chord books, the symbol "dim" or "o" represents a diminished seventh chord (a four-tone chord), which in some modern jazz books and music theory books is represented by the "dim7" or "o7" symbols. For example, the diminished triad built on B, written as Bo, has pitches B-D-F: The chord can be represented by the integer notation {0, 3, 6}. In the common practice period, the diminished triad was considered dissonant because of the diminished fifth (or tritone).

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