Chapter 2: Problem 18
Sketch, on the same coordinate plane, the graphs of \(f\) for the given values of \(c\). (Make use of symmetry, shifting, stretching, compressing, or reflecting.) $$f(x)=\sqrt{9-x^{2}}+c ; \quad c=-3,0,2$$
Short Answer
Expert verified
Graph semicircles centered at y = 0, -3, and 2 with endpoints at x = -3 and x = 3.
Step by step solution
01
Understand the Function
The function given is \( f(x) = \sqrt{9 - x^2} + c \). It represents a semicircle with radius 3 centered at the origin on the x-axis, because \( \sqrt{9 - x^2} \) is the equation of a semicircle. The parameter \( c \) vertically shifts this semicircle.
02
Graph the Parent Function
Graph \( f_0(x) = \sqrt{9 - x^2} \) first, which represents the top half of a circle with radius 3 centered at the origin, having domain \(-3 \le x \le 3\) and range \(0 \le y \le 3\).
03
Apply Vertical Shift for \(c = 0\)
For \( c = 0 \), the function is \( f(x) = \sqrt{9 - x^2} \). This is the same as the parent function and is already graphed in the previous step.
04
Apply Vertical Shift for \(c = -3\)
For \( c = -3 \), the function becomes \( f(x) = \sqrt{9 - x^2} - 3 \). This shifts the parent semicircle down by 3 units, so now the range is \(-3 \le y \le 0\).
05
Apply Vertical Shift for \(c = 2\)
For \( c = 2 \), the function becomes \( f(x) = \sqrt{9 - x^2} + 2 \). This shifts the parent semicircle up by 2 units, resulting in a new range of \(2 \le y \le 5\).
06
Sketch the Combined Graphs
Plot all three functions on the same coordinate plane. They are semicircles centered at the x-axis with respective vertical shifts determined by \( c = 0, -3, \) and \(2\). Their endpoints remain \( x = -3 \) and \( x = 3 \) for each function.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertical Shifts
Vertical shifts are a type of transformation that involve moving the graph of a function up or down along the y-axis. This is done by adding or subtracting a constant value, noted as \( c \), to the function. In the case of the function \( f(x) = \sqrt{9 - x^2} + c \), \( c \) determines how much the graph of the semicircle is shifted vertically.
For example:
For example:
- When \( c = 0 \), there is no vertical shift, so the semicircle remains in its original position.
- For \( c = -3 \), the semicircle shifts down 3 units, altering the range of the function.
- If \( c = 2 \), the shift is 2 units upwards.
Semicircle Equations
The semicircle equation \( y = \sqrt{a^2 - x^2} \) represents the top half of a circle with radius \( a \). In this exercise, the equation is \( y = \sqrt{9 - x^2} \), which forms a semicircle with radius 3. This semicircle is centered on the x-axis at the origin, stretching from \( x = -3 \) to \( x = 3 \).
Here are some key aspects of semicircle equations:
Here are some key aspects of semicircle equations:
- The domain is restricted by the radius, ensuring \(-a \leq x \leq a\).
- The range starts at 0 and goes up to the radius since it's only half of a full circle.
- This equation inherently has symmetry: it mirrors across the y-axis.
Function Sketching
Sketching functions involves a few key steps to capture essential features such as shape, position, and transformations. For our function \( f(x) = \sqrt{9 - x^2} + c \), consider these aspects:
- Start by sketching the parent function \( y = \sqrt{9-x^2} \), a semicircle centered at the origin.
- Use symmetry to assist your sketching; the graph reflects over the y-axis.
- Apply vertical shifts based on the value of \( c \) to sense the function elevation.
- Mark endpoints on the x-axis at \( x = -3 \) and \( x = 3 \).
Domains and Ranges
Domains and ranges are fundamental concepts that define where a function exists and the values it can take. Understanding these ideas is crucial for sketching correct graphs.
- The domain of our semicircle function \( f(x) = \sqrt{9 - x^2} + c \) is limited by the circle equation and is \(-3 \le x \le 3\). This shows that the function only exists within this interval on the x-axis.
- The range depends on the vertical shift value \( c \).
- For \( c = 0 \), the range is \(0 \le y \le 3\).
- With \( c = -3 \), it adjusts to \(-3 \le y \le 0\).
- For \( c = 2 \), it becomes \(2 \le y \le 5\).