The graph y = cos (x) would look like this:
Then you just adjust it to fit the other coeffiencients given. In this question the amplitude (the number before the cosine) is 1/2, this means the maxiumums and minimums will be 1/2 and -1/2. The frequency is the term that is multiplied with the x term inside the cosine, in this question it is 2, so the graph will have 2 cycles everytime this one has 1. So the graph will start at y = 1/2 then the first x intercept will be at pi/4 then the first minimum will be at pi/2, then there will be another x intercept at 3*pi/4 and etc. It should look like this:
