The graph of a tangent function is given. Select the equation for each graph from the following options: y = tan(x + π/2), y = tan(x + π), y = -tan x, y = −tan(x − π/2).
Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions

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Blitzer 3rd Edition
Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Problem 3
Blitzer 3rd Edition
Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Problem 3Chapter 2, Problem 3
Graph one period of each function. y = 2 tan x/2
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Identify the given function: \(y = 2 \tan \left( \frac{x}{2} \right)\).
Recall the basic properties of the tangent function \(\tan x\): it has vertical asymptotes where its argument equals \(\frac{\pi}{2} + k\pi\), for any integer \(k\), and its period is \(\pi\).
Determine the period of the transformed function \(\tan \left( \frac{x}{2} \right)\) using the formula for the period of \(\tan(bx)\), which is \(\frac{\pi}{|b|}\). Here, \(b = \frac{1}{2}\), so the period is \(\pi \div \frac{1}{2} = 2\pi\).
Find the vertical asymptotes by solving \(\frac{x}{2} = \frac{\pi}{2} + k\pi\), which gives \(x = \pi + 2k\pi\). For one period, consider \(k=0\) to find asymptotes at \(x = \pi\) and \(x = -\pi\).
Plot the graph between the vertical asymptotes \(x = -\pi\) and \(x = \pi\), noting that the function is scaled vertically by a factor of 2, so the values of \(\tan \left( \frac{x}{2} \right)\) are multiplied by 2.

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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 standard tangent function, y = tan(x), has a period of π, meaning it repeats every π units. When the function is modified to y = tan(bx), the period changes to π/|b|. For y = 2 tan(x/2), the coefficient inside the tangent is 1/2, so the period is π divided by 1/2, which equals 2π.
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Amplitude and Vertical Stretch
Although tangent functions do not have a maximum or minimum value, the coefficient outside the function, here 2, vertically stretches the graph. This means the output values are multiplied by 2, making the graph steeper and the values grow faster, but it does not affect the period or asymptotes.
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Stretches and Shrinks of Functions
Vertical Asymptotes of Tangent Functions
Tangent functions have vertical asymptotes where the function is undefined, occurring at points where the cosine in the denominator is zero. For y = tan(bx), asymptotes occur at x = (π/2 + kπ)/b, where k is any integer. For y = 2 tan(x/2), asymptotes are at x = π + 2kπ, guiding the graph's shape and domain restrictions.
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Asymptotes
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