Find constants a, b and c such that
The Attempt at a Solution
I expressed sin in its complex form (if thats what its called) and put it to the power 5, and then multiplied each bracket out one at a time, and got the correct answers, as checked by wolfram, but I was wondering if there is a quicker way to find the bracket to the power 5 other than just multiplying each bracket out 5 times with its self? This is probably a simple question but I never seem to be able to get the simple stuff. Any help is greatly appreciated. Thanks.
Sorry for the wording; I don't know how to use latex, and it's really ugly just typed out.