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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 29

In Exercises 29–44, graph two periods of the given cosecant or secant function. y = 3 csc x

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Recall that the cosecant function is the reciprocal of the sine function, so \(y = 3 \csc x\) can be written as \(y = \frac{3}{\sin x}\).
Identify the period of the basic \(\csc x\) function, which is \(2\pi\). Since there is no horizontal stretch or compression in \(y = 3 \csc x\), the period remains \(2\pi\).
To graph two periods, determine the interval over which to graph: from \(0\) to \(4\pi\) (since one period is \(2\pi\), two periods is \(4\pi\)).
Find the key points where \(\sin x = 0\) because \(\csc x\) is undefined there, causing vertical asymptotes. These occur at \(x = 0, \pi, 2\pi, 3\pi, 4\pi\) within the interval.
Plot the reciprocal values of \(\sin x\) scaled by 3, noting that the graph will have branches going to \(\pm \infty\) near the vertical asymptotes, and the minimum and maximum values of \(y = 3 \csc x\) correspond to \(y = \pm 3\) at points where \(\sin x = \pm 1\).

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Key Concepts

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

Understanding the Cosecant Function

The cosecant function, csc(x), is the reciprocal of the sine function, defined as csc(x) = 1/sin(x). It is undefined where sin(x) = 0, leading to vertical asymptotes at these points. Recognizing its behavior helps in accurately sketching its graph.
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Graphs of Secant and Cosecant Functions

Periodicity of Trigonometric Functions

The period of the basic cosecant function is 2π, meaning the function repeats its values every 2π units along the x-axis. Graphing two periods involves plotting the function over an interval of length 4π to capture two full cycles.
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Period of Sine and Cosine Functions

Amplitude and Vertical Stretch

The coefficient 3 in y = 3 csc x vertically stretches the graph by a factor of 3. This affects the distance of the graph's branches from the x-axis, increasing the minimum and maximum values of the function's range accordingly.
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Stretches and Shrinks of Functions