So far I just tried to do the obvious and substitute -a for - sin b. Like so;
sin 2x = - sin b
which then becomes;
sin 2x = sin -b
and then I can remove the sines and rearrange for x, which gives me this.
2x = -b
x = -b/2
However, if I were to look at the domain of b. Any value within the domain will give a value that doesn't fit the domain of x. Any suggestions would be great. Thank you!