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

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