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Waiting for your response.

Problem:	f(x) = - cos 3 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 =