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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 5

Graph two periods of the given tangent function. y = 3 tan x/4

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1
Identify the given function: \(y = 3 \tan \left( \frac{x}{4} \right)\).
Recall that the standard tangent function \(y = \tan x\) has a period of \(\pi\). For \(y = \tan(bx)\), the period is \(\frac{\pi}{b}\). Here, rewrite the argument as \(\frac{x}{4} = \left( \frac{1}{4} \right) x\), so \(b = \frac{1}{4}\).
Calculate the period of the function: \(\text{Period} = \frac{\pi}{b} = \frac{\pi}{\frac{1}{4}} = 4\pi\).
Since the problem asks to graph two periods, determine the interval for \(x\) that covers two periods: from \(0\) to \(8\pi\) (or any interval of length \(8\pi\)).
Plot the function \(y = 3 \tan \left( \frac{x}{4} \right)\) over the interval covering two periods, marking key points such as zeros (where the tangent argument is \(0, \pi, 2\pi, \ldots\)), vertical asymptotes (where the tangent argument is \(\frac{\pi}{2}, \frac{3\pi}{2}, \ldots\)), and the general shape scaled by the amplitude factor 3.

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Key Concepts

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

Period of the Tangent Function

The period of the basic tangent function y = tan x is π. When the function is transformed to y = tan(bx), the period changes to π divided by the absolute value of b. Understanding how to calculate the period is essential for correctly graphing the function over the specified intervals.
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Introduction to Tangent Graph

Amplitude and Vertical Stretch

Although the tangent function does not have a maximum or minimum amplitude, the coefficient outside the function, such as 3 in y = 3 tan(x/4), vertically stretches the graph. This affects the steepness of the curve but does not change the period or asymptotes.
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Stretches and Shrinks of Functions

Vertical Asymptotes of Tangent

Tangent functions have vertical asymptotes where the function is undefined, occurring at x-values where the cosine is zero. For y = tan(bx), asymptotes occur at x = (π/2 + kπ)/b for all integers k. Identifying these asymptotes is crucial for accurately sketching the graph.
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Asymptotes