Music theory homework help

[WRX07]

I would be very grateful if someone could help me. The assignment is to write:an Imperfect Authentic Cadence in A Major, a Perfect Authentic Cadence in D Minor, and a Half Cadence in E-flat Major. I know scales, thirds, fifths, etc, but I'm not sure how to write the cadences. Each one has to have two different measures with soprano, alto, tenor, and bass. The teacher did something where he wrote the triads for the chords and then crossed them out once he used them for the SATB. Again, I would be VERY grateful for any help.

[Nick Batzdorf]

A perfect authentic cadence goes V -> I. An imperfect authentic cadence also goes V -> I, but not in root position. A half cadence stops on V.

[WRX07]

Still having a bit of trouble .

Ok, let's say I'm writing the Imperfect Authentic Cadence(V->I) for A Major. The Bass for Imperfect is E(V) then A(I) but how do I know what the Soprano, Alto, and Tenor are? Sorry for the basic questions, I'm just starting to really get into theory (been self taught for 5 years) and it's really kicking my butt for putting it off so long.

[RobMacki]

SATB will have the triad contained in it (A=A,C#,E) (E=E,G#,B) etc. plus a doubled note or passing, suspension or anticipation note in the chord.
You will need to memorize all the chords in all the keys and be able to spell them.

A PAC I believe is I>IV>I6/4>V7>I.
An IAC is I>IV>V>I.

You may have inversions with the bass and your instructor will most likely want the the bass and sop in contrary motion with no parallel 5th or octaves within any of the voices.

HTH

[RobMacki]

I just looked it up in my Harvard Dic of Music (good resource to have) a PAC must have the tonic in the soprano.

[IntelDoc]

Here this may help?

http://www.musictheory.halifax.ns.ca/22cadences.html

- Doc

[WRX07]

Got it. Thanks a lot guys