If $ cos \;\alpha + cos \;\beta + cos \;\gamma = 0 = sin \;\alpha + sin \;\beta + sin \; \gamma $, prove that $ sin \;3\alpha \; + \;sin \;3\beta + sin \;3\gamma = 3 sin\left ( \alpha\; + \;\beta\; + \;\gamma \;\right )\Large$

Question

This is the second part of the multi-part Q3.