Question 4 is basically a straightforward pattern recognition. Look up the definitions of amplitude, period, etc. in your text (or online). For instance, the amplitude is the constant in front of the trig function of the form Acos(ax - by). You need to understand those concepts, and how they impact the graph of those functions. Only through understanding the examples you are provided can you learn it, and it is a straight application of their definitions and functional form.

As for the other questions, they all stem from understanding the reference angle. It is a rather easy idea. Again, consult your textbook. The reference angle is the angle between the angle you're given (from 0, say) and the x-axis. So 30 degrees is just 30 degrees from the reference angle. Now suppose we have 150 degrees. It's reference angle is in relation to the x-axis it is nearest. In this case, how far is 150 from 180? In this case, the answer is the same as the last one: 30 degrees. This should come as no surprise as 150 and 30 are symmetric to each other between those two quandrants.

If you can understand that, and understand the information you are given, the solution is nothing more than simple arithmetic, mostly. It also helps to understand what the sin and cos represent on the unit circle. Try to answer the questions and let us know what progress you have made.