The graph of a sinusoidal function intersects its midline at (0,−2) and then has a minimum point at (23π,−7).Write the formula of the function, where x is entered in radians.f(x)=
Q. The graph of a sinusoidal function intersects its midline at (0,−2) and then has a minimum point at (23π,−7).Write the formula of the function, where x is entered in radians.f(x)=
Determine Midline: Determine the midline of the sinusoidal function. The midline is the horizontal line that the function oscillates around. Since the function intersects the midline at (0,−2), the midline is y=−2.
Determine Amplitude: Determine the amplitude of the function.The amplitude is the distance from the midline to the maximum or minimum point of the function. Since the minimum point is at (23π,−7), and the midline is at y=−2, the amplitude is ∣−7−(−2)∣=5.
Determine Period: Determine the period of the function.Since the minimum point occurs at x=23π, and this is the first minimum point after the function intersects the midline, we can infer that the period is twice this value. Therefore, the period is 2×23π=3π.
Determine Value of B: Determine the value of B in the function f(x)=Acos(Bx+C)+D. The period of a sinusoidal function is given by B2π. Since the period is 3π, we have B2π=3π. Solving for B gives B=3π2π=32.
Determine Phase Shift: Determine the phase shift, C, of the function.Since the function intersects the midline at x=0, there is no horizontal shift, so C=0.
Write Function Equation: Write the equation of the sinusoidal function.We have determined the following values:Amplitude A=5B=32C=0Midline D=−2The function is a cosine function that has been vertically shifted down, so it will be of the form f(x)=Acos(Bx+C)+D. Substituting the values we found, we get f(x)=5cos(32x)−2.
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