Skip to main content
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 53

In Exercises 53–54, let f(x) = 2 sec x, g(x) = −2 tan x, and h(x) = 2x − π/2. Graph two periods of y = (f∘h)(x).

Guida verificata passo dopo passo
1
Understand the composition of functions: The function \( (f \circ h)(x) \) means \( f(h(x)) \). Given \( f(x) = 2 \sec x \) and \( h(x) = 2x - \frac{\pi}{2} \), substitute \( h(x) \) into \( f \) to get \( (f \circ h)(x) = 2 \sec(2x - \frac{\pi}{2}) \).
Recall the period of the secant function: The basic secant function \( \sec x \) has a period of \( 2\pi \). When the argument is modified to \( 2x - \frac{\pi}{2} \), the period changes according to the coefficient of \( x \).
Calculate the new period: For a function \( \sec(bx + c) \), the period is \( \frac{2\pi}{|b|} \). Here, \( b = 2 \), so the period of \( \sec(2x - \frac{\pi}{2}) \) is \( \frac{2\pi}{2} = \pi \).
Determine the interval for two periods: Since one period is \( \pi \), two periods will span \( 2 \times \pi = 2\pi \). So, the graph of \( y = 2 \sec(2x - \frac{\pi}{2}) \) should be drawn over an interval of length \( 2\pi \) in \( x \).
Identify key points and asymptotes: To graph the function, find where the argument \( 2x - \frac{\pi}{2} \) equals values that cause vertical asymptotes in \( \sec \), such as \( \frac{\pi}{2} + k\pi \), and plot points accordingly to capture the shape over two periods.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
5m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Function Composition

Function composition involves applying one function to the result of another, denoted as (f∘h)(x) = f(h(x)). Understanding how to substitute h(x) into f(x) is essential for rewriting and analyzing the composite function before graphing.
Video consigliato:
Percorso guidato
3:48
Evaluate Composite Functions - Special Cases

Secant Function and Its Properties

The secant function, sec x, is the reciprocal of cosine, sec x = 1/cos x. It has vertical asymptotes where cos x = 0 and a period of 2π. Knowing its shape, asymptotes, and period helps in accurately graphing transformations of sec x.
Video consigliato:
Percorso guidato
6:22
Graphs of Secant and Cosecant Functions

Period of a Composite Trigonometric Function

The period of a composite function like f(h(x)) depends on the inner function h(x). For h(x) = 2x − π/2, the horizontal scaling affects the period of sec x. Calculating the new period is crucial to graphing the function over the correct interval.
Video consigliato:
Percorso guidato
3:48
Evaluate Composite Functions - Special Cases