Math Problem Statement

The curve above is the graph of a sinusoidal function. It goes through the points
( − 4 , 0 ) and
( 2 , 0 ) . Write an equation of the form
f ( x )

A sin ( B ( x − D ) ) whose graph matches the given graph. f ( x )

Solution

To find the equation of the sinusoidal function f(x)=Asin(B(xD))f(x) = A \sin(B(x - D)), let's follow these steps:

1. Determine the period:

The sine function has zeros at x=4x = -4 and x=2x = 2, meaning these are consecutive zeros of the sine wave. The distance between them is 2(4)=62 - (-4) = 6. This distance represents half of a full period of the sine wave, so the full period is: Period=2×6=12\text{Period} = 2 \times 6 = 12

2. Find BB:

The period of a sine function is related to BB by the formula: Period=2πB\text{Period} = \frac{2\pi}{B} Substituting the known period: 12=2πB12 = \frac{2\pi}{B} Solving for BB: B=2π12=π6B = \frac{2\pi}{12} = \frac{\pi}{6}

3. Determine DD (Phase Shift):

Since the sine function typically starts at x=0x = 0, but here the sine wave has a zero at x=4x = -4, the function has been shifted horizontally. This shift is DD, and it corresponds to the first zero point at x=4x = -4. Therefore, D=4D = -4.

4. Determine AA (Amplitude):

From the problem, we know the sine function passes through (x=4,y=0)(x = -4, y = 0) and (x=2,y=0)(x = 2, y = 0), but we don't have explicit information about the maximum or minimum values of the sine function. However, assuming the standard sine function shape, we can set the amplitude A=1A = 1, unless other information is provided to suggest otherwise.

Final Equation:

The equation of the sinusoidal function is: f(x)=sin(π6(x+4))f(x) = \sin\left(\frac{\pi}{6}(x + 4)\right)

Would you like more details on any part of this process?


Here are 5 questions to extend this topic:

  1. How does changing the value of AA affect the graph of the sinusoidal function?
  2. What happens to the graph if you change the value of BB?
  3. How can we modify the equation if the sine function had a maximum at x=4x = -4?
  4. What would the equation be if the curve was a cosine function instead of a sine function?
  5. How can you determine the vertical shift of a sinusoidal function?

Tip: The period of any sinusoidal function can be easily calculated using the formula 2πB\frac{2\pi}{|B|}, where BB is the coefficient of xx inside the sine or cosine function.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Sinusoidal Functions
Phase Shift
Amplitude
Period

Formulas

f(x) = A sin(B(x − D))
Period = 2π / B
Phase Shift = D

Theorems

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Suitable Grade Level

Grades 10-12