Math Problem Statement

The graph of a sinusoidal function has a minimum point at (0, -10) and then has a maximum point at (2, -4). Write the formula of the function, where x is entered in radians.

Solution

To find the formula of the sinusoidal function, we can use the general form of a sine function:

f(x)=Asin(B(xC))+Df(x) = A \sin(B(x - C)) + D

where:

  • AA is the amplitude,
  • BB affects the period of the function,
  • CC is the phase shift,
  • DD is the vertical shift.

Step 1: Determine the Amplitude AA

The amplitude is the vertical distance from the midline to either the maximum or minimum point. The maximum is at 4-4 and the minimum is at 10-10, so the amplitude AA is: A=MaxMin2=4(10)2=62=3A = \frac{\text{Max} - \text{Min}}{2} = \frac{-4 - (-10)}{2} = \frac{6}{2} = 3

Step 2: Find the Midline DD

The midline DD is the average of the maximum and minimum values: D=Max+Min2=4+(10)2=142=7D = \frac{\text{Max} + \text{Min}}{2} = \frac{-4 + (-10)}{2} = \frac{-14}{2} = -7

Step 3: Determine the Period and BB

The period of a sine function is the distance required for the function to complete one full cycle. Here, the minimum point is at x=0x = 0 and the maximum point is at x=2x = 2. This distance represents a quarter period (since a sine function goes from minimum to maximum in a quarter cycle), so the full period TT is: T=4×2=8T = 4 \times 2 = 8 Since B=2πTB = \frac{2\pi}{T}, we have: B=2π8=π4B = \frac{2\pi}{8} = \frac{\pi}{4}

Step 4: Determine the Phase Shift CC

Since the minimum occurs at x=0x = 0, we don't need a phase shift. Therefore, C=0C = 0.

Step 5: Write the Equation

Substitute A=3A = 3, B=π4B = \frac{\pi}{4}, C=0C = 0, and D=7D = -7 into the formula:

f(x)=3sin(π4x)7f(x) = 3 \sin\left(\frac{\pi}{4} x \right) - 7

Final Answer

The formula for the sinusoidal function is:

f(x)=3sin(π4x)7f(x) = 3 \sin\left(\frac{\pi}{4} x \right) - 7

Would you like more details, or do you have any questions?


Here are 5 related questions to expand your understanding:

  1. How would the formula change if the minimum point were at (0,12)(0, -12)?
  2. What would happen if there was a phase shift in the function?
  3. How can we derive the formula if the points were given in degrees instead of radians?
  4. What effect does changing the amplitude AA have on the graph of the function?
  5. How would the function change if the period were halved?

Tip: Remember that the period of a sinusoidal function is determined by the coefficient BB, where T=2πBT = \frac{2\pi}{B}.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Sinusoidal Functions
Amplitude
Period
Phase Shift
Vertical Shift

Formulas

f(x) = A sin(B(x - C)) + D
Amplitude = (Max - Min) / 2
Midline D = (Max + Min) / 2
Period T = 2π / B

Theorems

Properties of sinusoidal functions

Suitable Grade Level

Grades 10-12