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The graph of a sinusoidal function intersects its midline at (0,2)(0,-2) and then has a minimum point at (3pi2,7)(\frac{3pi}{2},-7). Write the formula of the function, where xx is entered in radians.

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Q. The graph of a sinusoidal function intersects its midline at (0,2)(0,-2) and then has a minimum point at (3pi2,7)(\frac{3pi}{2},-7). Write the formula of the function, where xx is entered in radians.
  1. Determine Parameters: We need to determine the amplitude, midline, period, and phase shift of the sinusoidal function. The midline is given by the yy-coordinate of the point where the graph intersects the midline, which is 2-2. This gives us the value of DD in the general equation f(x)=Acos(Bx+C)+Df(x) = A\cos(Bx + C) + D.
  2. Find Amplitude: The minimum point of the function is at (3π/2,7)(3\pi/2, -7). Since the minimum point is 55 units below the midline (from 2-2 to 7-7), the amplitude of the function is 55. This gives us the value of AA in the general equation.
  3. Deduce Period: The period of the function is not directly given, but we can infer it from the fact that the minimum point occurs at 3π/23\pi/2. Since a minimum point of a cosine function occurs at 3π/2+2πk3\pi/2 + 2\pi k, where kk is an integer, we can deduce that the period is 2π2\pi. This gives us the value of BB in the general equation, which is 11 because the period TT is given by T=2π/BT = 2\pi/B, so B=2π/T=2π/2π=1B = 2\pi/T = 2\pi/2\pi = 1.
  4. Calculate Phase Shift: The phase shift CC can be determined by the fact that the graph intersects its midline at x=0x = 0. For a cosine function, this would normally happen at x=π2+2πkx = \frac{\pi}{2} + 2\pi k, but since it happens at x=0x = 0, we can deduce that there is a phase shift of π2-\frac{\pi}{2}. This gives us the value of CC in the general equation.
  5. Write Sinusoidal Function: Now we can write the equation of the sinusoidal function using the values of AA, BB, CC, and DD that we have found. The equation is:\newlinef(x)=Acos(Bx+C)+Df(x) = A\cos(Bx + C) + D\newlinef(x)=5cos(1xπ2)2f(x) = 5\cos(1x - \frac{\pi}{2}) - 2

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