longest chord = diameter

y = longest chord

y = diameter

radius = 1/2 diameter

therefore, radius = 1/2y

Supertonic - tonic cadence = Chord 2 followed by chord 1.

You should only have two notes in the treble of chord 1. Make sure that the bass part and leading note go to the tonic and add the 3rd note of the chord somewhere in the treble.

In a circle, there are 1 or more chords, and only always 1 diameter. The diameter goes through the middle point in a circle and connects 2 points on a circle. A chord does not have to go through the middle, but can. The diameter always counts as a chord.

So, either, both the chord and diameter are the same length, or the chord is shorter.

I hope this answers your question! (:

A chord that is tonic is the 1 or I chord of the music that you are playing. It is the key of the music that you are playing. If the tonic is C major then you would be playing in the key of C major and dominant or 5 chord would be G major.