SOLUTION: The desert temperature oscillates sinusoidally between 40◦F at 5am to 80◦F at 5pm, then down again to 40◦F at 5am the next day. Let the temperature, H, in fahrenh

Algebra ->  Trigonometry-basics -> SOLUTION: The desert temperature oscillates sinusoidally between 40◦F at 5am to 80◦F at 5pm, then down again to 40◦F at 5am the next day. Let the temperature, H, in fahrenh      Log On


   



Question 1082416: The desert temperature oscillates sinusoidally between 40◦F at 5am to 80◦F at 5pm, then down again to 40◦F at 5am the next day. Let the temperature, H, in fahrenheit, be a function of the time t, in hours since 5am.
Sketch a graph of H against t over a 72 hour period, from t = 0.
Find a formula for H in terms of t.

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Amplitude is 1/2 the range,
A=%281%2F2%29%2880-40%29=%281%2F2%29%2840%29=20
Mean value is the average of the two extremes,
T%5Bm%5D=%2880%2B40%29%2F2=120%2F2=60
Time to complete one cycle (period) is,
t%5BP%5D=12%2B12=24
So the period is P=%282pi%29%2F24=pi%2F12
Doesn't start at mean value, it starts at the lower extreme so there is a phase angle. Dial it back one quarter period.

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So putting it all together,
H=60%2B20sin%28%28pi%2F12%29t-pi%2F2%29
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