I got stuck again on this problem.

-(cos(-9pi/4)-sin(-9pi/4))^{2}-(cos 4pi/3 - sin 4pi/3)^{2 }

I used the unit circle to simplify and got this far:

Bracket 1: -(sqrt2/2-(-sqrt 2/2))^{2}=(-sqrt 2+sqrt 2/2)^{2}=(2 sqrt 2/2)^{2}=2

Bracket 2:-(-1/2-sqrt 2/2)^{2}= -(-1-sqrt 2/2)^{2}

After this im not getting any further and the answer is supposed to be c+ sqrt a/b, I know it's complicated but i really need help!!