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Ch. 4 - Graphs of the Circular Functions
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 5, Problem 3

Fill in the blank(s) to correctly complete each sentence.
The graph of y = 4 sin x is obtained by stretching the graph of y = sin x vertically by a factor of ________.

Verified step by step guidance
1
Identify the base function and the transformed function. Here, the base function is \(y = \sin x\) and the transformed function is \(y = 4 \sin x\).
Recall that the coefficient in front of the sine function affects the amplitude, which is the vertical stretch or compression of the graph.
The amplitude of \(y = \sin x\) is 1, since the sine function oscillates between -1 and 1.
The amplitude of \(y = 4 \sin x\) is 4, meaning the graph is stretched vertically by a factor equal to the amplitude.
Therefore, the vertical stretch factor is the ratio of the new amplitude to the original amplitude, which is \(4\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Amplitude of a Sine Function

The amplitude of a sine function y = a sin x is the absolute value of the coefficient 'a'. It represents the maximum vertical distance from the midline (usually the x-axis) to the peak of the wave, indicating how tall or stretched the graph is.
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Amplitude and Reflection of Sine and Cosine

Vertical Stretching of Graphs

Vertical stretching occurs when the output values of a function are multiplied by a factor greater than 1, increasing the distance from the x-axis. For y = a sin x, if |a| > 1, the graph is stretched vertically by a factor of |a| compared to y = sin x.
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Stretches and Shrinks of Functions

Basic Sine Function Graph

The basic sine function y = sin x has an amplitude of 1 and a period of 2π. Understanding its shape and properties is essential to recognize how changes in coefficients affect the graph, such as vertical stretches or compressions.
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Graph of Sine and Cosine Function