Final answer:
The formula for the desert temperature H in terms of time t (hours from 4am) is H = 20 cos(πt/6) + 50, with A = 20, B = π/6, and C = 50.
Step-by-step explanation:
The student asks for a formula for the temperature of the desert, H, as a function of time, t, using the form H = A cos(Bt) + C. To write this formula, we need to determine the values of A, B, and C.
To find A, which is the amplitude, we calculate the difference between the maximum and minimum temperatures and then divide by 2: A = (70°F - 30°F) / 2 = 20°F.
Next, to find B, which represents the frequency, we need to consider that the oscillation period is 12 hours (from 4am to 4pm). Therefore, B = 2π / period = 2π / 12 = π/6.
The value of C, which is the vertical shift, is the average of the maximum and minimum temperatures: C = (70°F + 30°F) / 2 = 50°F.
So, our final formula for H in terms of t measured in hours from 4am is H = 20 cos(πt/6) + 50.