Skip to main content
Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601당신이 사용하는 게 아니라요?교과서 변경
2장, 문제 34

Graph two periods of the given cosecant or secant function.


y = 3 sec x

검증된 단계별 안내
1
Recall that the secant function is defined as the reciprocal of the cosine function: \(y = \sec x = \frac{1}{\cos x}\). Therefore, \(y = 3 \sec x\) can be written as \(y = \frac{3}{\cos x}\).
Identify the period of the basic secant function. Since \(\cos x\) has a period of \(2\pi\), the secant function also has a period of \(2\pi\). So, one period of \(y = 3 \sec x\) spans an interval of length \(2\pi\).
To graph two periods, determine the interval over which you will plot the function. For example, from \(x = 0\) to \(x = 4\pi\) covers two full periods of \(y = 3 \sec x\).
Find the vertical asymptotes of the function by locating where \(\cos x = 0\), because \(\sec x\) is undefined there. These occur at \(x = \frac{\pi}{2} + k\pi\), where \(k\) is any integer. Mark these asymptotes within your chosen interval.
Plot key points by evaluating \(y = 3 \sec x\) at values where \(\cos x\) is \(\pm 1\) or other convenient points, such as \(x = 0, \pi, 2\pi, 3\pi, 4\pi\). Use these points and the asymptotes to sketch the two periods of the graph, noting that the graph will have branches opening upwards or downwards depending on the sign of \(\cos x\).

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
7m
도움이 되었나요?

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Secant Function and Its Properties

The secant function, sec(x), is the reciprocal of the cosine function, defined as sec(x) = 1/cos(x). It has vertical asymptotes where cos(x) = 0, causing the function to be undefined at these points. Understanding its periodicity and behavior near asymptotes is essential for graphing.
추천 영상:
6:22
Graphs of Secant and Cosecant Functions

Amplitude and Vertical Stretch

In the function y = 3 sec x, the coefficient 3 represents a vertical stretch, scaling the secant graph by a factor of 3. This affects the distance of the graph's branches from the x-axis but does not change the location of asymptotes or the period.
추천 영상:
6:02
Stretches and Shrinks of Functions

Periodicity of Secant Function

The secant function has a fundamental period of 2π, meaning its pattern repeats every 2π units along the x-axis. Graphing two periods involves plotting the function from 0 to 4π (or an equivalent interval), including all asymptotes and key points within this range.
추천 영상:
6:22
Graphs of Secant and Cosecant Functions