Chapter 9: Problem 28
Find the (a) period, (b) phase shift (if any), and (c) range of each function. $$y=2+\cot \left(2 x-\frac{\pi}{3}\right)$$
Short Answer
Expert verified
Period: \(\frac{\pi}{2}\), Phase Shift: \(\frac{\pi}{6}\) right, Range: \((-\infty, \infty)\).
Step by step solution
01
Identify the standard form
The standard form for the cotangent function is \(y = a + b \cdot \cot(c(x - d))\), where \(a\) is the vertical shift, \(b\) is the amplitude (not applicable for cotangent functions as they don't have a maximum or minimum), \(c\) affects the period, and \(d\) affects the phase shift.
02
Determine the period
The period of a cotangent function is calculated using the formula \( \frac{\pi}{|c|} \). In our equation, we have \(c = 2\). Therefore, the period is \( \frac{\pi}{2} \).
03
Calculate the phase shift
The phase shift (horizontal shift) of the cotangent function can be found from the term \(c(x-d)\) in the standard form. Rearrange the equation inside the cotangent to match \(c(x-d)\). We have: \(2x - \frac{\pi}{3} = 2(x - \frac{\pi}{6})\). Thus, the phase shift is \(\frac{\pi}{6}\) units to the right.
04
Determine the range
The range of a cotangent function is always \((-\infty, \infty)\) since cotangent functions continue indefinitely in both directions along the y-axis without bound. The vertical shift does not affect the range.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Period of a Function
When working with trigonometric functions like cotangent, understanding the concept of the period is essential. The period of a function is the length of the smallest interval over which the function repeats its values. For a basic cotangent function, \( ext{cot}(x)\), the period is usually \( ext{Ï€}\).
However, modifications to the function such as multiplication by a constant can change this period.
For instance, in the expression \(y = 2 + \cot\left(2x - \frac{\pi}{3}\right)\), the term that affects the period is the multiplier before \(x\), which is 2 in this case.
Using the formula \( \frac{\pi}{|c|} \), where \(c\) is the multiplier, we find that the period of this function becomes \( \frac{\pi}{2} \). Thus, the function completes one cycle every \( \frac{\pi}{2} \).
However, modifications to the function such as multiplication by a constant can change this period.
For instance, in the expression \(y = 2 + \cot\left(2x - \frac{\pi}{3}\right)\), the term that affects the period is the multiplier before \(x\), which is 2 in this case.
Using the formula \( \frac{\pi}{|c|} \), where \(c\) is the multiplier, we find that the period of this function becomes \( \frac{\pi}{2} \). Thus, the function completes one cycle every \( \frac{\pi}{2} \).
- The general formula for the period of a cotangent function: \( \frac{\pi}{|c|} \)
- Input from our specific function: \( \frac{\pi}{2} \)
- Why periods matter: They tell us how often the function repeats.
Phase Shift
Phase shift in trigonometric functions involves a horizontal shift along the x-axis. In terms of the function \(y = a + b \cdot \cot(c(x - d))\), this is determined by the term inside the function where \(d\) is directly indicative of the shift.
For the equation \(y = 2 + \cot\left(2x - \frac{\pi}{3}\right)\), we first rewrite the expression inside the cotangent function to reflect our standard form: \(2(x - \frac{\pi}{6})\).
For the equation \(y = 2 + \cot\left(2x - \frac{\pi}{3}\right)\), we first rewrite the expression inside the cotangent function to reflect our standard form: \(2(x - \frac{\pi}{6})\).
- This rearrangement shows us that the expression shifts the function \(\frac{\pi}{6}\) units to the right.
- Key takeaway: The phase shift indicates where the start of a new cycle is located compared to the origin.
- The concept ensures we know how the graph's cycle is adjusted horizontally.
Range of Trigonometric Functions
Understanding the range of a function helps us know the possible values output by the function on the y-axis. Trigonometric functions have specific ranges.
For the cotangent function, \( \text{cot}(x) \), the output can extend indefinitely, meaning its range is \(( -\infty, \infty )\).
Even after accounting for vertical shifts like in \(y = 2 + \cot\left(2x - \frac{\pi}{3}\right)\), the range remains the same.
For the cotangent function, \( \text{cot}(x) \), the output can extend indefinitely, meaning its range is \(( -\infty, \infty )\).
Even after accounting for vertical shifts like in \(y = 2 + \cot\left(2x - \frac{\pi}{3}\right)\), the range remains the same.
- Vertical shifts affect the position but not the range of cotangent.
- The y-values possible for a cotangent function will always cover all real numbers.
- The independence of range from vertical shifts emphasizes the unbounded nature of cotangent outputs.