G dim/A
The G dim chord consists of the G (Perfect unison), Bb (Minor third) and Db (Diminished fifth) notes, with A as the bass note.

How to play the G dim/A chord
- Play A as the lowest bass note in the left hand
- Find G (Root) on the piano keyboard
- Add Bb (Minor third) — 3 semitones above G
- Add Db (Diminished fifth) — 6 semitones above G
- Press all 4 notes simultaneously to sound the G dim/A chord