Chapter 6: Problem 1
Determine the amplitude, the period, and the phase shift of the function and, without a graphing calculator, sketch the graph of the function by hand. Then check the graph using a graphing calculator. $$y=\sin x+1$$
Short Answer
Expert verified
Amplitude: 1, Period: 2\pi, Phase shift: 0. Shift the sine curve up by 1 unit.
Step by step solution
01
Identify the amplitude
The amplitude of a sine function in the form \(y=a\sin(bx+c)+d\) is given by the absolute value of \(a\). In this case, the function is \(y=\sin x+1\), implying that \(a=1\). Therefore, the amplitude is \(\left|1\right|=1\).
02
Determine the period
The period of a sine function \(y=a\sin(bx+c)+d\) is given by \(\frac{2\pi}{b}\). Here, \(b=1\). Therefore, the period is \(\frac{2\pi}{1}=2\pi\).
03
Calculate the phase shift
The phase shift of a sine function \(y=a\sin(bx+c)+d\) is determined by solving \(bx+c=0\). In this function, \(c=0\), so there is no phase shift.
04
Determine the vertical shift
The vertical shift of the function \(y=a\sin(bx+c)+d\) is determined by \(d\). In this case, \(d=1\), so the whole graph is shifted up by 1 unit.
05
Sketch the graph
To sketch \(y=\sin x+1\), start by plotting the basic sine curve \(y=\sin x\). Then, shift the entire graph up by 1 unit. Points like \(0, 1\), \(\pi/2, 2\), \(\pi, 1\), \(3\pi/2, 0\), and \(2\pi, 1\) can be plotted for accuracy.
06
Verify using a graphing calculator
After sketching the graph by hand, input \(y=\sin x+1\) into a graphing calculator to verify the plotted graph matches the calculated shifts and shape.
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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, specifically the sine function, refers to how much the graph oscillates above and below its central axis. For a function in the form \(y = a\sin(bx + c) + d\), the amplitude is given by the absolute value of the coefficient \(a\). In the case of the function \(y = \sin(x) + 1\), the coefficient \(a\) is 1. This means the amplitude is \( \left| 1 \right| = 1\). The graph will oscillate 1 unit above and below the central axis.
Period
The period of a sine function is the length of one complete cycle on the graph. For a general sine function \(y = a\sin(bx + c) + d\), the period is calculated using the formula \(\frac{2\pi}{b}\). For the function \(y = \sin(x) + 1\), \(b = 1\). Therefore, the period is \(\frac{2\pi}{1} = 2\pi\). This means the function repeats its pattern every \(2\pi\) units along the x-axis.
Phase Shift
The phase shift of a sine function determines how the graph is horizontally shifted from its usual position. For a sine function \(y = a\sin(bx + c) + d\), the phase shift is calculated by solving \(bx + c = 0\). In our function \(y = \sin(x) + 1\), we have \(c = 0\), which means there is no horizontal shift. Consequently, there is no change in the starting point of the sine wave on the x-axis due to phase shift.
Vertical Shift
The vertical shift of a sine function determines how the graph is shifted up or down along the y-axis. For the function \(y = a\sin(bx + c) + d\), the vertical shift is given by \(d\). In the function \(y = \sin(x) + 1\), \(d = 1\). This means that the entire graph of the sine function is shifted upward by 1 unit. Therefore, the midline of the graph moves from \(y = 0\) to \(y = 1\).
Sine Function
The sine function, \( \sin(x) \), is a fundamental trigonometric function characterized by its wave-like shape. It is periodic, meaning it repeats at regular intervals, and is symmetrical around its midline. For the standard sine function \(y = \sin(x)\), the graph oscillates between -1 and 1, has a period of \(2\pi\), and no phase or vertical shifts. In our modified function \(y = \sin(x) + 1\), we see some changes:
- The amplitude remains 1, as the coefficient of \(\sin(x)\) is 1.
- The period is still \(2\pi\), meaning the pattern repeats every \(2\pi\) units.
- There is no phase shift since the function does not contain a horizontal translation component.
- The vertical shift is 1, which shifts the graph upwards by 1 unit, moving the midline to \(y = 1\).
- At \(x = 0\), \(y = 1\)
- At \(x = \pi/2\), \(y = 2\)
- At \(x = \pi\), \(y = 1\)
- At \(x = 3\pi/2\), \(y = 0\)
- At \(x = 2\pi\), \(y = 1\)