G# Viennese trichord/C
The G# Viennese trichord chord consists of the G# (Perfect unison), A (Minor second) and D (Diminished fifth) notes, with C as the bass note.

How to play the G# Viennese trichord/C chord
- Play C as the lowest bass note in the left hand
- Find G# (Root) on the piano keyboard
- Add A (Minor second) — 1 semitone above G#
- Add D (Diminished fifth) — 6 semitones above G#
- Press all 4 notes simultaneously to sound the G# Viennese trichord/C chord