Chapter 7: Problem 148
Graph each circle. Identify the center and the radius. \((x-1)^{2}+(y+3)^{2}=16\)
Short Answer
Expert verified
Center: \((1, -3)\), Radius: \4\.
Step by step solution
01
Identify the standard form of a circle equation
Compare the given equation \((x - 1)^2 + (y + 3)^2 = 16\) with the standard form \((x - h)^2 + (y - k)^2 = r^2\), where \(h, k\) is the center and \(r\) is the radius.
02
Determine the center of the circle
From the equation \((x-1)^2 + (y+3)^2 = 16\), identify \((h, k) = (1, -3)\). Thus, the center of the circle is \((1, -3)\).
03
Determine the radius of the circle
Compare the given radius term with \((r^2)\). Here, \(r^2 = 16\) which means \(r = \sqrt{16} = 4\). The radius of the circle is \4\.
04
Graph the circle
Plot the center of the circle at \((1, -3)\). Draw a circle with a radius of \4\ units around this center point.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
standard form of a circle
Understanding the standard form of a circle's equation is crucial for identifying key features such as the center and the radius. The standard form of a circle's equation is \((x - h)^2 + (y - k)^2 = r^2\).
This compact form tells us everything we need to know about the circle:
This compact form tells us everything we need to know about the circle:
- The terms \(h\) and \(k\) represent the x and y coordinates of the center of the circle, respectively.
- The term \(r\) represents the radius of the circle, which is the distance from the center to any point on the circle.
center of a circle
To find the center of a circle, we need to look at the terms inside the squared parentheses in the standard form equation \((x - h)^2 + (y - k)^2 = r^2\).
The center of the circle is represented by the coordinates \( (h, k) \).
The center of the circle is represented by the coordinates \( (h, k) \).
- In the given equation \((x - 1)^2 + (y + 3)^2 = 16\), we compare and find that \( h = 1 \) and \( k = -3 \).
- So, the center of the circle is at the point \((1, -3)\).
radius of a circle
Calculating the radius of a circle involves understanding the term \(r^2\) in the standard form equation \((x - h)^2 + (y - k)^2 = r^2\).
The radius \(r\) is simply the square root of the given constant term.
The radius \(r\) is simply the square root of the given constant term.
- For the equation \((x - 1)^2 + (y + 3)^2 = 16\), we recognize that \(r^2 = 16\).
- Taking the square root of both sides, we get \(r = \sqrt{16}\ = 4\).
graphing circles
Graphing a circle becomes straightforward once we identify the center and the radius. To plot the circle given by \((x - 1)^2 + (y + 3)^2 = 16\) on a graph:
- Start by plotting the center at the point \( (1, -3) \) on the coordinate plane.
- Next, use a compass or a consistent scale to draw a circle with a radius of 4 units around this center point.