Chapter 10: Problem 8
Find the amplitude and period of each function and then sketch its graph. $$y=-\frac{1}{5} \sin 5 x$$
Short Answer
Expert verified
Amplitude: \( \frac{1}{5} \); Period: \( \frac{2\pi}{5} \). Reflects the sine wave vertically.
Step by step solution
01
Identify the General Form
The general form of the sine function is given by \( y = a \sin(bx + c) + d \). For the function \( y = -\frac{1}{5} \sin 5x \), we identify: - \( a = -\frac{1}{5} \) which affects the amplitude.- \( b = 5 \) which affects the period. - \( c = 0 \) and \( d = 0 \) meaning there are no horizontal or vertical shifts.
02
Calculate the Amplitude
The amplitude of a sine function \( y = a \sin(bx) \) is the absolute value of \( a \). Here, \( a = -\frac{1}{5} \), so the amplitude is \( |-\frac{1}{5}| = \frac{1}{5} \).
03
Calculate the Period
The period of a sine function is given by \( \frac{2\pi}{b} \). For \( b = 5 \), the period is \( \frac{2\pi}{5} \). This is the length of one complete cycle of the sine wave along the x-axis.
04
Sketch the Graph
To sketch the graph of \( y = -\frac{1}{5} \sin 5x \), note the following:- Amplitude is \( \frac{1}{5} \), so the graph will oscillate between \( \frac{1}{5} \) and \( -\frac{1}{5} \).- Period is \( \frac{2\pi}{5} \), so one full wave cycle will occur within this length on the x-axis.- The negative \( a \) causes a reflection in the x-axis. Start at the origin and draw a sine curve considering these values.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Amplitude
The amplitude of a trigonometric function describes its vertical stretch or compression, specifically the maximum distance from the function's midline to its peak. In the function we are working with, \[ y = -\frac{1}{5} \sin 5x \]we identify the amplitude using the coefficient of the sine function. Here, the coefficient is \(-\frac{1}{5}\). Although it is negative, when finding amplitude, we take the absolute value.
- The amplitude is \(\left|-\frac{1}{5}\right| = \frac{1}{5}\).
- This means the sine wave will oscillate, reaching up to \(\frac{1}{5}\) above, and \(-\frac{1}{5}\) below its midline.
Period
The period of a sine function such as \[ y = -\frac{1}{5} \sin 5x \]is the length of one complete wave cycle along the x-axis. It is determined by the coefficient \(b\) of the \(x\) term in the sine function. The formula to compute the period is:\[ \text{Period} = \frac{2\pi}{b} \]In this exercise, with \(b = 5\), we calculate:
- Period = \(\frac{2\pi}{5}\).
- This tells us that the sine function will complete one full cycle over an interval of \(\frac{2\pi}{5}\) units on the x-axis, giving it a relatively fast oscillation rate compared to a standard sine wave.
Sine Wave Graph
Sketching the graph of the function \[ y = -\frac{1}{5} \sin 5x \]requires understanding both the amplitude and period, alongside general properties of the sine function. Key details for sketching include:
- the wave begins at 0, moves downward first due to the negative sign, - hits \(-\frac{1}{5}\) at a quarter of the period, - returns to 0 at half the period value, - reaches \(\frac{1}{5}\), and - finally returns to 0 completing the cycle. Keep in mind these trigonometric waves continue indefinitely in both directions unless otherwise specified.
- Amplitude: Since it is \(\frac{1}{5}\), the wave oscillates between \(\frac{1}{5}\) and \(-\frac{1}{5}\).
- Period: The function completes a full cycle over the length \(\frac{2\pi}{5}\).
- Reflection: The negative sign in front of the amplitude reflects the wave, flipping it upside down across the x-axis.
- the wave begins at 0, moves downward first due to the negative sign, - hits \(-\frac{1}{5}\) at a quarter of the period, - returns to 0 at half the period value, - reaches \(\frac{1}{5}\), and - finally returns to 0 completing the cycle. Keep in mind these trigonometric waves continue indefinitely in both directions unless otherwise specified.