(i) Use the fact that you know that sin(v)=sin(180-v)
(ii) Use the fact that you know that -cos(v)=cos(180-v)
When you're facing problems involving angles that you "haven't seen" earlier in the problem, the solution often has something to do with the trig. identities! keep it in mind and learn how to derive them from the unit circle (the basic onces)!