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Find an equation for a sinusoidal function that has period 2Ο€2\pi, amplitude 22, and contains the point (3Ο€2,0)\left(\frac{3\pi}{2}, 0\right). Write your answer in the form f(x)=Acos⁑(Bx+C)+Df(x)=A\cos(Bx+C)+D, where AA, BB, CC, and DD are real numbers.

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Q. Find an equation for a sinusoidal function that has period 2Ο€2\pi, amplitude 22, and contains the point (3Ο€2,0)\left(\frac{3\pi}{2}, 0\right). Write your answer in the form f(x)=Acos⁑(Bx+C)+Df(x)=A\cos(Bx+C)+D, where AA, BB, CC, and DD are real numbers.
  1. Determine B Value: Determine the value of B using the given period of the function.\newlineSince the period of a cosine function is given by (2Ο€)/B(2\pi)/B, we can set this equal to the given period of 2Ο€2\pi and solve for B.\newlinePeriod: (2Ο€)/B=2Ο€(2\pi)/B = 2\pi\newlineB=(2Ο€)/(2Ο€)B = (2\pi)/(2\pi)\newlineB=1B = 1
  2. Set Amplitude and B: Since the amplitude is given as 22, we know that A=2A = 2. So far, we have:\newlinef(x)=2cos⁑(Bx+C)+Df(x) = 2\cos(Bx + C) + D\newlineSubstituting B=1B = 1, we get:\newlinef(x)=2cos⁑(x+C)+Df(x) = 2\cos(x + C) + D
  3. Find C and D Values: Next, we need to determine the values of C and D. Since the function contains the point (3Ο€/2,0)(3\pi/2, 0), we can substitute x=3Ο€/2x = 3\pi/2 and f(x)=0f(x) = 0 into the equation and solve for C and D.\newline0=2cos⁑(3Ο€/2+C)+D0 = 2\cos(3\pi/2 + C) + D\newlineSince cos⁑(3Ο€/2)=0\cos(3\pi/2) = 0, the equation simplifies to:\newline0=2(0)+D0 = 2(0) + D\newlineD=0D = 0
  4. Determine Phase Shift: Now we need to find the value of CC. We know that the cosine function has a value of 00 at 3Ο€2\frac{3\pi}{2} when it is at the mid-point between its maximum and minimum values. Since the amplitude is 22, the maximum and minimum values are 22 and βˆ’2-2, respectively. Therefore, the cosine function must be at 3Ο€2\frac{3\pi}{2} for the first time at the mid-point of its period, which is Ο€\pi. This means that the phase shift CC must be such that x+C=Ο€x + C = \pi when 0000.\newline0011\newline0022\newline0033
  5. Substitute Values for Final Equation: Substitute the values of AA, BB, CC, and DD into the general form of the equation to get the final equation of the sinusoidal function.\newlinef(x)=2cos⁑(xβˆ’Ο€2)+0f(x) = 2\cos(x - \frac{\pi}{2}) + 0\newlinef(x)=2cos⁑(x+Ο€2)f(x) = 2\cos(x + \frac{\pi}{2}) (since cosine is an even function, cos⁑(βˆ’ΞΈ)=cos⁑(ΞΈ)\cos(-\theta) = \cos(\theta))

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