Question 1176527
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A high temperature of 94 and an average temperature of 75 means the amplitude is 94-75=19 and the midline is 75.<br>
The basic cosine function is at its maximum value at t=0; since we are given that the maximum temperature is at 6pm, we can model the temperature with a cosine function in which t=0 at 6pm.<br>
{{{T(t) = 19cos(t)+75}}}<br>
t is 0 at 6pm; the period of the cosine function is 2pi.  A time of 7am is 13 hours after 6pm, so a time of 7am is represented by an angle of 13/24 time 2pi, or 13/12 times pi.<br>
Use a calculator to evaluate T(t) at t=(13/12)pi.<br>