Table of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
4. Graphing Trigonometric Functions
Graphs of the Sine and Cosine Functions
Problem 9
Textbook Question
In Exercises 7–16, determine the amplitude and period of each function. Then graph one period of the function. y = 3 sin 1/2 x
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1
Identify the general form of the sine function, which is \( y = a \sin(bx + c) + d \). In this case, \( y = 3 \sin\left(\frac{1}{2}x\right) \).
Determine the amplitude of the function. The amplitude is the absolute value of \( a \), which is the coefficient in front of the sine function. Here, \( a = 3 \), so the amplitude is \( |3| = 3 \).
Find the period of the function. The period of a sine function is given by \( \frac{2\pi}{b} \), where \( b \) is the coefficient of \( x \) inside the sine function. Here, \( b = \frac{1}{2} \), so the period is \( \frac{2\pi}{\frac{1}{2}} = 4\pi \).
Graph one period of the function. Start at \( x = 0 \) and plot points at key intervals: \( x = 0 \), \( x = \pi \), \( x = 2\pi \), \( x = 3\pi \), and \( x = 4\pi \). The corresponding \( y \)-values will be \( 0 \), \( 3 \), \( 0 \), \( -3 \), and \( 0 \) respectively.
Draw the sine curve through these points, ensuring it reaches the maximum and minimum values at the appropriate intervals, completing one full cycle of the sine wave.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Amplitude
Amplitude refers to the maximum distance a wave reaches from its central axis or equilibrium position. In the context of sine functions, it is determined by the coefficient in front of the sine term. For the function y = 3 sin(1/2 x), the amplitude is 3, indicating that the wave oscillates between 3 and -3.
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Period
The period of a trigonometric function is the length of one complete cycle of the wave. For sine functions, the period can be calculated using the formula P = 2π / |b|, where b is the coefficient of x. In the function y = 3 sin(1/2 x), the coefficient is 1/2, resulting in a period of 4π, meaning the function repeats every 4π units along the x-axis.
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Graphing Trigonometric Functions
Graphing trigonometric functions involves plotting the function's values over a specified interval to visualize its behavior. For y = 3 sin(1/2 x), one period can be graphed from 0 to 4π, showing the wave's oscillation between its amplitude limits. Understanding the amplitude and period is crucial for accurately representing the function's shape and characteristics on a graph.
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