This is a chart to show how those chords are related C D E F G A B
C major C E G / E minor E G B / A minor A C E
D minor D F A / F major F A C
G major G B D / B dim B D F
As you can see A min and C maj share two notes C and E
As you can see C maj and E min share two notes E and G
As you can see D min and F maj share two notes F and A
As you can see G maj and B dim share two notes B and D
As you can see this chart help me out with chord progressions and how you can use substitutions for them.
Check it out:
All tonic - subdominant - dominant progression
I was wondering where that IV-V-vi come from.