Chapter 5: Problem 10
Graph the function. $$f(x)=-1+\cos x$$
Short Answer
Expert verified
The graph of \( f(x) = -1 + \cos x \) is a vertically shifted cosine wave oscillating between -2 and 0.
Step by step solution
01
Identify the Function Components
The function given is \( f(x) = -1 + \cos x \). This is a transformation of the basic cosine function \( \cos x \). The transformation involves shifting the graph vertically by -1 unit.
02
Determine Key Points of Cosine Function
The cosine function \( \cos x \) has a period of \( 2\pi \) and typically starts at \( (0, 1) \). Other key points include \( (\frac{\pi}{2}, 0) \), \( (\pi, -1) \), \( (\frac{3\pi}{2}, 0) \), and \( (2\pi, 1) \).
03
Apply Vertical Shift to Key Points
Adjust each of the key points of the \( \cos x \) function by shifting them 1 unit downward. This gives the transformed points: \( (0, 0) \), \( (\frac{\pi}{2}, -1) \), \( (\pi, -2) \), \( (\frac{3\pi}{2}, -1) \), and \( (2\pi, 0) \).
04
Sketch the Transformed Graph
Plot the points identified in the previous step on a coordinate plane. Draw a smooth curve passing through these points to complete one cycle of the transformed cosine function. The graph will oscillate between -2 and 0, peaking at 0 and reaching a trough at -2.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cosine Function
The cosine function, denoted as \( \cos x \), is one of the fundamental trigonometric functions. It describes the ratio of the adjacent side to the hypotenuse in a right-angled triangle. Mathematically, it is periodic and oscillates between the values of 1 and -1 over its domain of all real numbers.
Here are some essential characteristics of the basic cosine function:
Here are some essential characteristics of the basic cosine function:
- Amplitude: The maximum height (from the midline) of the wave is 1.
- Periodicity: The function repeats its pattern every \(2\pi\) units; hence, the period is \(2\pi\).
- Key Points: The typical points in one period are \((0, 1)\), \((\frac{\pi}{2}, 0)\), \((\pi, -1)\), \((\frac{3\pi}{2}, 0)\), and \((2\pi, 1)\).
Vertical Shift
A vertical shift in trigonometric functions involves moving the entire graph up or down on the coordinate plane. This is done by adding or subtracting a constant from the function.
Let's see how this applies to our function \( f(x) = -1 + \cos x \):
Let's see how this applies to our function \( f(x) = -1 + \cos x \):
- Effect of Vertical Shift: The graph of \( \cos x \) is moved downward by 1 unit.
- Impact on Key Points: Each point on the original cosine graph is lowered by 1 unit.
- The point \((0, 1)\) becomes \((0, 0)\). - New Range: The range of the transformed function is now from -2 to 0.
Periodicity of Trigonometric Functions
Trigonometric functions like cosine exhibit periodicity, which means they repeat their values in a predictable pattern.
For the cosine function:
For the cosine function:
- Period: The time it takes for the cosine function to complete one full cycle is \(2\pi\). This is the length along the x-axis after which the function starts to repeat.
- Understanding Periodicity: Knowing the period of a function helps in plotting the graph efficiently, as you can expect the function to reproduce its shape over each interval of length \(2\pi\).
- Application to Transformed Functions: Even when transformations like vertical shifts are applied, the period of the function remains unaffected.