Identifying the Phase Shift

Oct 13, 2025 by wbrum.org 130 views

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Introduction

Sinusoidal functions are a fundamental concept in mathematics, particularly in the field of trigonometry. These functions are characterized by their periodic and oscillatory nature, with a smooth, continuous curve that repeats itself over a fixed interval. In this article, we will explore how to find the sinusoidal function that corresponds to a given graph.

Understanding the Graph

The graph provided shows a sinusoidal function that passes through the points (-70, 0) and (3, 0). This means that the function has a period of 73 units (the distance between the two points) and has a maximum or minimum value at the point (3, 0).

Identifying the Amplitude

The amplitude of a sinusoidal function is the distance from the midline to the maximum or minimum value of the function. In this case, since the function passes through the point (3, 0), the midline is the x-axis, and the amplitude is the distance from the x-axis to the point (3, 0). This distance is 3 units.

Identifying the Period

The period of a sinusoidal function is the distance between two consecutive points on the graph that have the same y-value. In this case, the period is 73 units, as mentioned earlier.

Identifying the Phase Shift

The phase shift of a sinusoidal function is the horizontal distance between the point where the function starts and the point where it reaches its maximum or minimum value. In this case, since the function passes through the point (3, 0), the phase shift is 3 units.

Writing the Sinusoidal Function

Now that we have identified the amplitude, period, and phase shift, we can write the sinusoidal function in the form:

y = A sin(B(x - C)) + D

where A is the amplitude, B is the frequency (1/period), C is the phase shift, and D is the vertical shift.

In this case, A = 3, B = 1/73, C = 3, and D = 0 (since the midline is the x-axis).

Substituting the Values

Substituting the values of A, B, C, and D into the equation, we get:

y = 3 sin((1/73)(x - 3)) + 0

Simplifying the Equation

Simplifying the equation, we get:

y = 3 sin((x - 3)/73)

Conclusion

In this article, we have shown how to find the sinusoidal function that corresponds to a given graph. We identified the amplitude, period, and phase shift of the function and used this information to write the function in the form y = A sin(B(x - C)) + D. We then substituted the values of A, B, C, and D into the equation and simplified it to get the final answer.

The Final Answer

The sinusoidal function that corresponds to the given graph is:

y = 3 sin((x - 3)/73)

Graph of the Function

Here is a graph of the function:

import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(-100, 100, 400)
y = 3 * np.sin((x - 3) / 73)
plt.plot(x, y)
plt.xlabel('x')
plt.ylabel('y')
plt.title('Graph of the Sinusoidal Function')
plt.grid(True)
plt.axhline(0, color='black')
plt.axvline(0, color='black')
plt.show()

This graph shows the sinusoidal function that corresponds to the given graph. The function has a period of 73 units and passes through the points (-70, 0) and (3, 0).

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Introduction

In our previous article, we explored how to find the sinusoidal function that corresponds to a given graph. We identified the amplitude, period, and phase shift of the function and used this information to write the function in the form y = A sin(B(x - C)) + D. In this article, we will answer some common questions related to sinusoidal functions.

Q: What is the difference between a sinusoidal function and a periodic function?

A: A periodic function is a function that repeats itself over a fixed interval, but it does not have to be a sinusoidal function. A sinusoidal function, on the other hand, is a specific type of periodic function that has a smooth, continuous curve and is characterized by its oscillatory nature.

Q: How do I determine the amplitude of a sinusoidal function?

A: The amplitude of a sinusoidal function is the distance from the midline to the maximum or minimum value of the function. To determine the amplitude, you can use the formula:

A = |y_max - y_min| / 2

where y_max is the maximum value of the function and y_min is the minimum value of the function.

Q: How do I determine the period of a sinusoidal function?

A: The period of a sinusoidal function is the distance between two consecutive points on the graph that have the same y-value. To determine the period, you can use the formula:

T = 2π / B

where T is the period and B is the frequency (1/period).

Q: How do I determine the phase shift of a sinusoidal function?

A: The phase shift of a sinusoidal function is the horizontal distance between the point where the function starts and the point where it reaches its maximum or minimum value. To determine the phase shift, you can use the formula:

C = -π / B

where C is the phase shift and B is the frequency (1/period).

Q: What is the difference between a sine function and a cosine function?

A: A sine function is a sinusoidal function of the form y = A sin(B(x - C)) + D, while a cosine function is a sinusoidal function of the form y = A cos(B(x - C)) + D. The only difference between the two is the sign of the B term.

Q: Can I use a sinusoidal function to model real-world phenomena?

A: Yes, sinusoidal functions can be used to model many real-world phenomena, such as the motion of a pendulum, the vibration of a spring, and the oscillation of a circuit.

Q: How do I graph a sinusoidal function?

A: To graph a sinusoidal function, you can use a graphing calculator or a computer program such as Python's matplotlib library. You can also use a graphing app on your smartphone or tablet.

Q: Can I use a sinusoidal function to model a non-periodic phenomenon?

A: No, sinusoidal functions are only used to model periodic phenomena. If you want to model a non-periodic phenomenon, you will need to use a different type of function, such as a polynomial or an exponential function.

Q: How do I find the equation of a sinusoidal function that passes through two points?

A: To find the equation of a sinusoidal function that passes through two points, you can use the following steps:

Determine the amplitude, period, and phase shift of the function.
Use the formula y = A sin(B(x - C)) + D to write the equation of the function.
Substitute the values of A, B, C, and D into the equation.
Simplify the equation to get the final answer.

Example

Suppose we want to find the equation of a sinusoidal function that passes through the points (2, 3) and (4, -2). We can use the following steps:

Determine the amplitude, period, and phase shift of the function.
Use the formula y = A sin(B(x - C)) + D to write the equation of the function.
Substitute the values of A, B, C, and D into the equation.
Simplify the equation to get the final answer.

import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0, 10, 400)
y = 3 * np.sin((x - 2) / 2) + 1
plt.plot(x, y)
plt.xlabel('x')
plt.ylabel('y')
plt.title('Graph of the Sinusoidal Function')
plt.grid(True)
plt.axhline(0, color='black')
plt.axvline(0, color='black')
plt.show()

This graph shows the sinusoidal function that passes through the points (2, 3) and (4, -2). The function has an amplitude of 3, a period of 4, and a phase shift of 2.