a) You will need vector addition, which is just adding vectors componentwise.
b) Use the law of cosines
c) Use the formula where is the cross-product and is the magnitude.
d) Use the formula where is the dot-product.
If you don't understand those terms you will need to look them up. I believe your instructor intends for you to learn this on your own, so I won't be able to help you any further without an attempt at a solution.