Problem:f(x) = 3 cos 4 x. On a sheet of paper, graph the function in degrees. Determine the function's y-intercept, amplitude, interval, period, and the four x-values that mark the location of its quartiles. Responses: y-intercept = (, ) amplitude = interval = [, ] period = quartile 1 = quartile 2 = quartile 3 = quartile 4 =