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Sinusoidal models word problems

W(t)W(t) models the daily water level (in cm\text{cm}) at a pond in Arizona, tt days after the hottest day of the year. Here, tt is entered in radians.
W(t)=15cos(2π365t)+43W(t) = 15\cos\left(\dfrac{2\pi}{365}t\right) + 43
What is the first time after the hottest day of the year that the water level is 30 cm30 \text{ cm}?
Round your final answer to the nearest whole day.
  • Your answer should be
  • an integer, like 66
  • a simplified proper fraction, like 3/53/5
  • a simplified improper fraction, like 7/47/4
  • a mixed number, like 1 3/41\ 3/4
  • an exact decimal, like 0.750.75
  • a multiple of pi, like 12 pi12\ \text{pi} or 2/3 pi2/3\ \text{pi}
days