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Pluto's distance from the sun varies in a periodic way that can be modeled approximately by a trigonometric function.
Pluto's maximum distance from the sun (aphelion) is 7.4 billion kilometers. Its minimum distance from the sun (perihelion) is 4.4 billion kilometers. Pluto last reached its perihelion in the year 1989 , and will next reach its perihelion in 2237.
Find the formula of the trigonometric function that models Pluto's distance 
D from the sun (in billion km ) t years after 2000 . Define the function using radians.
D(t)=◻
How far will Pluto be from the sun in 2022 ? Round your answer, if necessary, to two decimal places.
◻ billion km

Pluto's distance from the sun varies in a periodic way that can be modeled approximately by a trigonometric function. \newlinePluto's maximum distance from the sun (aphelion) is 7.47.4 billion kilometers. Its minimum distance from the sun (perihelion) is 4.44.4 billion kilometers. Pluto last reached its perihelion in the year 19891989, and will next reach its perihelion in 22372237. \newlineFind the formula of the trigonometric function that models Pluto's distance DD from the sun (in billion km\text{km}) tt years after 20002000. Define the function using radians. \newlineD(t)=D(t)=\square \newlineHow far will Pluto be from the sun in 20222022? Round your answer, if necessary, to two decimal places. \newline\square billion km\text{km}

Full solution

Q. Pluto's distance from the sun varies in a periodic way that can be modeled approximately by a trigonometric function. \newlinePluto's maximum distance from the sun (aphelion) is 7.47.4 billion kilometers. Its minimum distance from the sun (perihelion) is 4.44.4 billion kilometers. Pluto last reached its perihelion in the year 19891989, and will next reach its perihelion in 22372237. \newlineFind the formula of the trigonometric function that models Pluto's distance DD from the sun (in billion km\text{km}) tt years after 20002000. Define the function using radians. \newlineD(t)=D(t)=\square \newlineHow far will Pluto be from the sun in 20222022? Round your answer, if necessary, to two decimal places. \newline\square billion km\text{km}
  1. Determine Amplitude: First, we need to determine the amplitude of the trigonometric function.\newlineThe amplitude is half the distance between the maximum and minimum values.\newlineAmplitude = (Maximum distanceMinimum distance)/2(\text{Maximum distance} - \text{Minimum distance}) / 2\newlineAmplitude = (7.4 billion km4.4 billion km)/2(7.4 \text{ billion km} - 4.4 \text{ billion km}) / 2\newlineAmplitude = 3 billion km/23 \text{ billion km} / 2\newlineAmplitude = 1.5 billion km1.5 \text{ billion km}
  2. Calculate Vertical Shift: Next, we calculate the vertical shift, which is the average of the maximum and minimum distances.\newlineVertical shift = (Maximum distance+Minimum distance)/2(\text{Maximum distance} + \text{Minimum distance}) / 2\newlineVertical shift = (7.4 billion km+4.4 billion km)/2(7.4 \text{ billion km} + 4.4 \text{ billion km}) / 2\newlineVertical shift = 11.8 billion km/211.8 \text{ billion km} / 2\newlineVertical shift = 5.9 billion km5.9 \text{ billion km}
  3. Find Period: Now, we need to find the period of the function. The period is the time it takes for Pluto to go from one perihelion to the next.\newlinePeriod = Next perihelion year - Last perihelion year\newlinePeriod = 223719892237 - 1989\newlinePeriod = 248248 years
  4. Convert to Radians: To define the function using radians, we need to convert the period into radians. Since the period is the time for a full cycle, it corresponds to 2π2\pi radians.\newlineRadians per year = 2πPeriod\frac{2\pi}{\text{Period}}\newlineRadians per year = 2π248\frac{2\pi}{248}
  5. Write Trigonometric Function: We can now write the trigonometric function for Pluto's distance from the sun. We will use a cosine function, which starts at a maximum value at t=0t=0 (year 20002000). We need to adjust the phase shift to account for the fact that the last perihelion was in 19891989, which is 1111 years before 20002000.
    Phase shift = Radians per year * (20002000 - Last perihelion year)
    Phase shift = (2π/248)(20001989)(2\pi / 248) * (2000 - 1989)
    Phase shift = (2π/248)11(2\pi / 248) * 11
  6. Calculate D(22)D(22): The trigonometric function that models Pluto's distance from the sun tt years after 20002000 is:\newlineD(t)=Amplitude×cos(Radians per year×tPhase shift)+Vertical shiftD(t) = \text{Amplitude} \times \cos(\text{Radians per year} \times t - \text{Phase shift}) + \text{Vertical shift}\newlineD(t)=1.5 billion km×cos(2π248×t2π248×11)+5.9 billion kmD(t) = 1.5 \text{ billion km} \times \cos\left(\frac{2\pi}{248} \times t - \frac{2\pi}{248} \times 11\right) + 5.9 \text{ billion km}
  7. Perform Calculation: To find how far Pluto will be from the sun in 20222022, we need to calculate D(t)D(t) for t=20222000t = 2022 - 2000.\newlinet=20222000t = 2022 - 2000\newlinet=22t = 22 years\newlineD(22)=1.5D(22) = 1.5 billion km ×cos(2π248×222π248×11)+5.9\times \cos\left(\frac{2\pi}{248} \times 22 - \frac{2\pi}{248} \times 11\right) + 5.9 billion km
  8. Final Result: Now we perform the calculation for D(22)D(22):
    D(22)=1.5D(22) = 1.5 billion km cos(2π248222π24811)+5.9* \cos\left(\frac{2\pi}{248} * 22 - \frac{2\pi}{248} * 11\right) + 5.9 billion km
    D(22)1.5D(22) \approx 1.5 billion km cos(0.558505360.27925268)+5.9* \cos(0.55850536 - 0.27925268) + 5.9 billion km
    D(22)1.5D(22) \approx 1.5 billion km cos(0.27925268)+5.9* \cos(0.27925268) + 5.9 billion km
    D(22)1.5D(22) \approx 1.5 billion km 0.9605305+5.9* 0.9605305 + 5.9 billion km
    D(22)1.44079575D(22) \approx 1.44079575 billion km D(22)=1.5D(22) = 1.500 billion km
    D(22)=1.5D(22) = 1.511 billion km
    Rounded to two decimal places, Pluto will be approximately D(22)=1.5D(22) = 1.522 billion km from the sun in 20222022.

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