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Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Non è quello che usi tu?Cambia libro di testo
Capitolo 2, Problema 43

In Exercises 43–52, determine the amplitude, period, and phase shift of each function. Then graph one period of the function. y = cos(x − π/2)

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Identify the general form of the cosine function: \(y = A \cos(B(x - C))\), where \(A\) is the amplitude, \(B\) affects the period, and \(C\) is the phase shift.
Compare the given function \(y = \cos(x - \frac{\pi}{2})\) to the general form. Here, \(A = 1\) (since there is no coefficient in front of cosine), \(B = 1\) (coefficient of \(x\)), and \(C = \frac{\pi}{2}\).
Calculate the amplitude, which is the absolute value of \(A\): \(\text{Amplitude} = |A| = 1\).
Calculate the period using the formula \(\text{Period} = \frac{2\pi}{|B|}\). Since \(B = 1\), the period is \(2\pi\).
Determine the phase shift, which is \(C\). Since the function is \(\cos(x - \frac{\pi}{2})\), the phase shift is \(\frac{\pi}{2}\) units to the right.

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Amplitude of a Trigonometric Function

Amplitude is the maximum absolute value of a trigonometric function from its midline. For functions like y = cos(x), the amplitude is the coefficient before the cosine term, indicating the height of peaks and depth of troughs. In y = cos(x − π/2), the amplitude is 1, as there is no coefficient other than 1.
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Introduction to Trigonometric Functions

Period of a Trigonometric Function

The period is the length of one complete cycle of the function, typically 2π for sine and cosine functions. It can be adjusted by a coefficient inside the function's argument. For y = cos(x − π/2), since the coefficient of x is 1, the period remains 2π.
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Period of Sine and Cosine Functions

Phase Shift of a Trigonometric Function

Phase shift refers to the horizontal translation of the graph, determined by the value added or subtracted inside the function's argument. For y = cos(x − π/2), the graph shifts π/2 units to the right, meaning the entire cosine curve moves rightward by π/2 along the x-axis.
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