Chapter 10: Problem 22
View at least two cycles of the graphs of the given functions on a calculator. $$y=12 \sec \left(2 x+\frac{\pi}{4}\right)$$
Short Answer
Expert verified
Graph the function over the interval from \( -\frac{\pi}{4} \) to \( \frac{7\pi}{4} \) to see two complete cycles.
Step by step solution
01
Understanding the Function
The given function is in the form of a secant function, i.e., \( y = 12 \sec\left(2x + \frac{\pi}{4}\right) \). The secant function is related to the cosine function, where \( \sec(x) = \frac{1}{\cos(x)} \). It has vertical asymptotes where the cosine is zero.
02
Identifying the Period
The period of \( \sec(kx + b) \) is determined by the coefficient \( k \). The period of \( \sec(x) \) is \( 2\pi \), thus for \( \sec(2x + \frac{\pi}{4}) \) the period is \( \frac{2\pi}{2} = \pi \). Since two cycles are needed, the interval should cover \( 2\pi \) units of \( x \).
03
Finding Vertical Asymptotes
Vertical asymptotes occur where \( \cos(2x + \frac{\pi}{4}) = 0 \). This happens for \( 2x + \frac{\pi}{4} = \frac{\pi}{2} + n\pi \), where \( n \) is an integer. Solving for \( x \) gives \( x = \frac{\pi}{8} + \frac{n\pi}{2} \).
04
Amplitude Adjustment
The function includes a multiplier of 12, which stretches the graph vertically. Therefore, the maximum values are 12 and minimum values are -12 at the peaks and troughs between the asymptotes.
05
Graphing Two Cycles
To graph two cycles with a calculator, set the domain to between the values for \( x \), i.e., from \( -\frac{\pi}{4} \) to \( \frac{7\pi}{4} \), which covers two full cycles of the graph. Input the function and check the display for the correct visualization.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Secant Function
The secant function is a trigonometric function closely related to the cosine function. Its mathematical definition is given by the reciprocal of the cosine function: \[\sec(x) = \frac{1}{\cos(x)}\]. This relationship means that the secant function is undefined whenever the cosine function equals zero.
- This leads to vertical asymptotes in the graph of the secant function, which visually represent these undefined points.
- Secant graphs exhibit a distinctive pattern of continuous curves alternating with vertical asymptotes.
Graphing Calculators
A graphing calculator is an essential tool for visualizing complex functions like the secant function. It allows students to input complicated equations and view their graphical representations accurately.
- Graphing calculators can handle various trigonometric transformations, including those with shifts and stretches like our given secant function.
- They allow for domain adjustment to visualize functions within specific intervals, crucial for viewing two cycles of a periodic function.
Periodicity in Trigonometry
Periodicity is a central feature of trigonometric functions, referring to the repeating pattern inherent in graphs like sine, cosine, and secant. For a standard secant function \( \sec(x) \), the period is \( 2\pi \), meaning the pattern repeats every \( 2\pi \) units.
- For transformations like \( \sec(kx + b) \), the period is adjusted according to the coefficient \( k \).
- The period becomes \( \frac{2\pi}{k} \), due to the horizontal compression or stretching caused by \( k \).