Answer: E) 0.9744
Step-by-step explanation:
This is something you'll need a calculator for. As far as I know, there isn't a clean formula that will allow you to compute this by hand, and get something like sqrt(3)/2. There is a way to find the decimal value by hand, but it will require knowledge of Taylor polynomials and it will take a very long while to compute the value. So again, it's better to use a calculator. When using a calculator, make sure it's in degree mode. You can check by computing cos(60) and you should get 0.5