Chapter 6: Problem 214
For the following exercises, sketch the graph of each function for two full periods. Determine the amplitude, the period, and the equation for the midline. $$ f(x)=5 \sin \left(3\left(x-\frac{\pi}{6}\right)\right)+4 $$
Short Answer
Expert verified
Amplitude: 5, Period: \( \frac{2\pi}{3} \), Midline: \( y=4 \).
Step by step solution
01
Identify the amplitude
The amplitude of a sinusoidal function given by the form \( f(x) = a \sin(b(x-c))+d \) is the absolute value of \( a \). For \( f(x) = 5 \sin(3(x-\frac{\pi}{6}))+4 \), the amplitude is \(|5| = 5\).
02
Determine the period
The period of a sine function \( f(x) = a \sin(b(x-c))+d \) is given by \( \frac{2\pi}{b} \). For this function, \( b = 3 \), so the period is \( \frac{2\pi}{3} \).
03
Find the midline
The midline of a sinusoidal function \( f(x) = a \sin(b(x-c))+d \) is the constant \( d \). For this function, \( d = 4 \). Thus, the equation for the midline is \( y = 4 \).
04
Sketch the graph
To sketch the graph for two full periods:1. Start at the phase shift \( x = \frac{\pi}{6} \).2. The first peak is at \( x = \frac{\pi}{6} + \frac{\pi}{6} = \frac{\pi}{3} \) with a value of \( 9 \).3. The first zero is at \( x = \frac{\pi}{6} + \frac{\pi}{3} = \frac{\pi}{2} \).4. The first trough is at \( x = \frac{\pi}{6} + \frac{\pi}{2} = \frac{2\pi}{3} \) with a value of \( -1 \).5. The pattern repeats every \( \frac{2\pi}{3} \).6. The midline \( y = 4 \) should be drawn as a reference line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Amplitude
In trigonometry, the amplitude of a sinusoidal function is an important concept. It measures the peak deviation of a wave from its midline. Essentially, it tells us how "tall" or "short" the wave is. The amplitude reflects both the maximum and minimum values a wave can reach.
For the function given, \( f(x) = 5 \sin(3(x-\frac{\pi}{6}))+4 \), the amplitude is represented by the absolute value of the coefficient before the sine function, which is \( |5| \).
For the function given, \( f(x) = 5 \sin(3(x-\frac{\pi}{6}))+4 \), the amplitude is represented by the absolute value of the coefficient before the sine function, which is \( |5| \).
- This means the amplitude is \( 5 \).
- This indicates that the wave reaches 5 units above and below the midline.
Period
The period of a sinusoidal function indicates how long it takes for the wave to repeat itself. This is crucial in a variety of applications, such as signal processing and sound waves. The period is determined by the coefficient \( b \) in the function \( f(x) = a \sin(b(x-c))+d \).
In our problem, the periodic value \( b \) is \( 3 \), leading to a period of \( \frac{2\pi}{b} \).
In our problem, the periodic value \( b \) is \( 3 \), leading to a period of \( \frac{2\pi}{b} \).
- This results in a period of \( \frac{2\pi}{3} \).
- The wave repeats its cycle every \( \frac{2\pi}{3} \) units.
Sinusoidal Functions
Sinusoidal functions, like sine and cosine, are fundamental in trigonometry. They produce wave-like patterns that are found in various fields, from physics to engineering. A sinusoidal function is generally written as \( f(x) = a \sin(b(x - c)) + d \). Each parameter plays a specific role in shaping the wave:
- \( a \) determines the amplitude.
- \( b \) influences the period.
- \( c \) represents the phase shift.
- \( d \) designates the vertical shift, creating the midline.
Midline
The midline of a sinusoidal function is the horizontal line around which the wave oscillates. It effectively splits the wave into two symmetric parts, indicating a balance point.In the function \( f(x) = 5 \sin(3(x-\frac{\pi}{6}))+4 \), the midline is derived from the constant \( d \).
- Here, \( d = 4 \), which gives us a midline represented by the equation \( y = 4 \).
- This serves as a reference line in graphing, helping to visualize the wave's central position.
Phase Shift
The phase shift in a sinusoidal function is a lateral shift along the x-axis. It affects where the wave starts relative to its standard position. Phase shifts are crucial when comparing different waves or synchronizing signals.
The value \( c \) in the equation \( f(x) = a \sin(b(x-c))+d \) determines the phase shift.
For the function \( f(x) = 5 \sin(3(x-\frac{\pi}{6}))+4 \),
The value \( c \) in the equation \( f(x) = a \sin(b(x-c))+d \) determines the phase shift.
For the function \( f(x) = 5 \sin(3(x-\frac{\pi}{6}))+4 \),
- The phase shift is \( \frac{\pi}{6} \).
- This means the wave begins \( \frac{\pi}{6} \) to the right of the origin.