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Ch. 4 - Graphs of the Circular Functions
Chapter 5, Problem 4.15

For each function, give the amplitude, period, vertical translation, and phase shift, as applicable.
y = 1/3 tan (3x - π/3)

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1
Identify the general form of the tangent function: \( y = a \tan(bx - c) + d \).
Determine the amplitude: For tangent functions, amplitude is not defined as they have no maximum or minimum values.
Calculate the period: The period of \( \tan(bx) \) is \( \frac{\pi}{b} \). Here, \( b = 3 \), so the period is \( \frac{\pi}{3} \).
Find the phase shift: The phase shift is given by \( \frac{c}{b} \). Here, \( c = \frac{\pi}{3} \) and \( b = 3 \), so the phase shift is \( \frac{\pi/3}{3} = \frac{\pi}{9} \).
Determine the vertical translation: The vertical translation is given by \( d \). In this function, \( d = 0 \), so there is no vertical translation.

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Key Concepts

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

Amplitude

In trigonometric functions, amplitude refers to the height of the wave from its midline to its peak. However, for the tangent function, amplitude is not defined as it does not have a maximum or minimum value; it extends infinitely in both directions. Instead, we focus on the vertical stretch or compression, which is determined by the coefficient in front of the function.
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Period

The period of a trigonometric function is the length of one complete cycle of the wave. For the tangent function, the period is calculated using the formula π divided by the coefficient of x in the argument. In this case, with a coefficient of 3, the period is π/3, indicating that the function repeats every π/3 units along the x-axis.
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Phase Shift

Phase shift refers to the horizontal displacement of a trigonometric function from its standard position. It is determined by the horizontal translation in the function's argument. For the function y = (1/3) tan(3x - π/3), the phase shift can be found by setting the inside of the tangent function equal to zero, leading to a shift of π/9 units to the right.
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