They want it "Simplified", well them wanting it "Simplified" is causing me heartache tryingn to get in into the computer system.
I can imagine. I would presume that "simplified" in this case would mean in terms of sine and cosine, but you could also argue that they want "as few functions as possible" or "no fractions." For no fractions and only two trig functions we could write this as:
Best of luck! (Go bother your professor about this. If your professor is going to make you use computer software that doesn't ask for an explicit form, then he/she deserves to be bothered! )