The question asks us to sketch the function y cos 3t First note that the function is a cosine function and will have that basic shape From the text the general form of a non shifted cosine function is y a cos bt The text also tells us that a is the amplitude that is the maximum height above zero that the function attains Note that the amplitude must be a positive number Looking at our function the amplitude is 1 1 Step 2 2x Next we need the period From the text the period of the function y a cos bt is b Looking at our function and simplifying the period is of complete cycles the function goes through between 0 and 2 More intuitively the number b gives the number