Chapter 15: Problem 6
Sketch \(y=3 \sin 2 A\) from \(A=0\) to \(A=2 \pi\) radians.
Short Answer
Expert verified
The sine wave oscillates between 3 and -3 with a period of \( \pi \).
Step by step solution
01
Understand the Function
The function given is in the form of \( y = a \sin(bA) \), where \( a = 3 \) and \( b = 2 \). This indicates that the amplitude of the function is 3 and the period is determined by dividing \( 2\pi \) by \( b \).
02
Determine the Amplitude
The amplitude of a sine function is the maximum value it reaches. In this function, \( a = 3 \), so the amplitude is 3. This means the sine wave will oscillate between 3 and -3.
03
Determine the Period
To find the period of \( y = 3 \sin(2A) \), use the formula for the period of a sine function: \( \text{Period} = \frac{2\pi}{b} = \frac{2\pi}{2} = \pi \). Thus, the sine wave completes one full cycle when \( A \) goes from 0 to \( \pi \).
04
Identify Key Points
The key points of one cycle of the sine wave \( y = 3 \sin(2A) \) occur at these values due to the period \( \pi \): \( A = 0, \frac{\pi}{4}, \frac{\pi}{2}, \frac{3\pi}{4}, \pi \). They correspond to \( y = 0, 3, 0, -3, 0 \) respectively.
05
Sketch the Function
Using the amplitude and period determined, sketch two cycles of the sine wave: Starting at 0, rising to 3 at \( \frac{\pi}{4} \), returning to 0 at \( \frac{\pi}{2} \), descending to -3 at \( \frac{3\pi}{4} \), and returning to 0 at \( \pi \). Repeat the wave from \( \pi \) to \( 2\pi \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Amplitude of Sine Waves
The amplitude of a sine wave is a fundamental concept in trigonometry, representing the height of the wave's peaks and valleys. In the function given, \( y = 3 \sin(2A) \), the amplitude is determined by the coefficient \( a \), which is 3 in this case.
Therefore, the sine wave oscillates between the maximum value of 3 and the minimum value of -3.
This indicates a vertical stretch, making the wave taller compared to the standard sine function, which oscillates between 1 and -1.
Therefore, the sine wave oscillates between the maximum value of 3 and the minimum value of -3.
This indicates a vertical stretch, making the wave taller compared to the standard sine function, which oscillates between 1 and -1.
- A larger amplitude implies a stronger wave, meaning more significant oscillations.
- The amplitude never changes over the domain; it consistently defines the vertical limits of the wave.
Period of Trigonometric Functions
The period of a trigonometric function like sine defines the interval length needed for the wave to complete one full cycle. In the function \( y = 3 \sin(2A) \), the period is calculated using the formula \( \text{Period} = \frac{2\pi}{b} \). Here, \( b = 2 \) modifies the typical period of a sine function.Substituting the values, the period becomes \( \frac{2\pi}{2} = \pi \).
This means the sine function completes a full wave cycle as \( A \) moves from 0 to \( \pi \).
This means the sine function completes a full wave cycle as \( A \) moves from 0 to \( \pi \).
- A smaller \( b \) value elongates the period, stretching the wave horizontally.
- A larger \( b \) value shortens the period, compressing the wave horizontally.
Sketching Graphs of Sine Functions
Sketching graphs of sine functions involves plotting key points and interpreting amplitude and period. For \( y = 3 \sin(2A) \), the amplitude is 3 and the period is \( \pi \). Understanding these elements allows for accurate sketching.To sketch one cycle:
Visualizing these points sketch by hand or using graphing software helps in understanding the sine function's wave pattern.
- Start at \( A = 0 \) with \( y = 0 \).
- At \( A = \frac{\pi}{4} \), the graph reaches its peak at 3.
- The graph returns to \( y = 0 \) at \( A = \frac{\pi}{2} \).
- At \( A = \frac{3\pi}{4} \), the graph dips to -3.
- Finally, it returns to \( y = 0 \) at \( A = \pi \).
Visualizing these points sketch by hand or using graphing software helps in understanding the sine function's wave pattern.