The key of A major
A B C♯ D E F♯ G♯
3 sharps: F♯ C♯ G♯. Relative minor: The key of F♯ minor.
The triads of the key
I
A | ii
Bm | iii
C♯m | IV
D | V
E | vi
F♯m | vii°
G♯° |
The seventh chords
Imaj7
Amaj7 | ii7
Bm7 | iii7
C♯m7 | IVmaj7
Dmaj7 | V7
E7 | vi7
F♯m7 | viiø7
G♯m7♭5 |
A major scale
Open it in the app: 6. Harmony, in A