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Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 2, Problem 30

Graph two periods of the given cosecant or secant function.


y = 2 csc x

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1
Identify the basic function: The given function is \( y = 2 \csc x \), which is a transformation of the cosecant function \( \csc x = \frac{1}{\sin x} \).
Determine the period: The period of \( \csc x \) is \( 2\pi \). Since there is no horizontal stretch or compression, the period of \( y = 2 \csc x \) remains \( 2\pi \).
Identify the vertical stretch: The coefficient 2 indicates a vertical stretch by a factor of 2. This means the maximum and minimum values of the cosecant function will be multiplied by 2.
Locate the vertical asymptotes: The vertical asymptotes of \( \csc x \) occur where \( \sin x = 0 \), which is at \( x = n\pi \) for integer \( n \). These will remain the same for \( y = 2 \csc x \).
Graph two periods: Plot the function over the interval \( [0, 4\pi] \), marking the vertical asymptotes at \( x = 0, \pi, 2\pi, 3\pi, 4\pi \), and sketch the curves of \( y = 2 \csc x \) between these asymptotes, showing the vertical stretch.

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Key Concepts

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

Cosecant Function

The cosecant function, denoted as csc(x), is the reciprocal of the sine function. It is defined as csc(x) = 1/sin(x). The cosecant function has vertical asymptotes where the sine function is zero, which occurs at integer multiples of π. Understanding the behavior of the sine function is crucial for graphing the cosecant function.
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Graphing Periodic Functions

Periodic functions repeat their values in regular intervals, known as periods. For the cosecant function, the period is 2π, meaning the function will repeat its pattern every 2π units along the x-axis. When graphing, it is essential to identify key points within one period to accurately represent the function over multiple periods.
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Amplitude and Vertical Stretch

The amplitude of a function refers to the height of its peaks from the midline. In the function y = 2 csc(x), the coefficient '2' indicates a vertical stretch, meaning the peaks of the cosecant function will be twice as high as the standard cosecant function. This affects the overall shape of the graph, making it important to consider when plotting the function.
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