Let the function P=f(t) denote the pressure in pipe at time t minutes. Find a possible formula for the function P=f(t) described above. Remember to use t as your input variable.

Question

The pressure  (in pounds per square foot), in a pipe varies over time. Two times an hour, the pressure oscillates from a low of 80 to a high of 210 and then back to a low of 80. The pressure at time t=0 is 80. 

Answer 1

The pressure should be P = 65cos(4*pi*t - pi) + 145

(I understand from the description that the period is 1/2 hour)