12. (x+7)* +(y+2)° = 108 Center: Area:

Elementary Geometry For College Students, 7e
7th Edition
ISBN:9781337614085
Author:Alexander, Daniel C.; Koeberlein, Geralyn M.
Publisher:Alexander, Daniel C.; Koeberlein, Geralyn M.
ChapterP: Preliminary Concepts
SectionP.CT: Test
Problem 1CT
Question
Identify each part of the circle given its equation
### Problem 12:

Given the equation of a circle:

\[ (x + 7)^2 + (y + 2)^2 = 108 \]

#### Questions to Answer:
1. **Find the Center of the Circle:**
   - The general form of the equation of a circle is \((x - h)^2 + (y - k)^2 = r^2\), where \((h, k)\) is the center of the circle and \(r\) is the radius.
   - In this given equation, \((x + 7)^2 + (y + 2)^2 = 108\), we can rewrite it as \((x - (-7))^2 + (y - (-2))^2 = 108\).
   - Therefore, the center of the circle is \((-7, -2)\).

2. **Find the Area of the Circle:**
   - In a circle's equation \((x - h)^2 + (y - k)^2 = r^2\), \(r^2 = 108\).
   - To find the radius \(r\), we take the square root of 108:
     \[
     r = \sqrt{108} = \sqrt{4 \times 27} = 2\sqrt{27}
     \]
   - The area \(A\) of a circle is given by the formula \(A = \pi r^2\).
   - Given \(r^2 = 108\), the area \(A\) is:
     \[
     A = \pi \times 108 = 108\pi
     \]

Therefore:
- **Center:** \((-7, -2)\)
- **Area:** \(108\pi\) square units.

Note: This transcription would be formatted to match the educational website's style guide, including appropriate spacing and formatting for clarity.
Transcribed Image Text:### Problem 12: Given the equation of a circle: \[ (x + 7)^2 + (y + 2)^2 = 108 \] #### Questions to Answer: 1. **Find the Center of the Circle:** - The general form of the equation of a circle is \((x - h)^2 + (y - k)^2 = r^2\), where \((h, k)\) is the center of the circle and \(r\) is the radius. - In this given equation, \((x + 7)^2 + (y + 2)^2 = 108\), we can rewrite it as \((x - (-7))^2 + (y - (-2))^2 = 108\). - Therefore, the center of the circle is \((-7, -2)\). 2. **Find the Area of the Circle:** - In a circle's equation \((x - h)^2 + (y - k)^2 = r^2\), \(r^2 = 108\). - To find the radius \(r\), we take the square root of 108: \[ r = \sqrt{108} = \sqrt{4 \times 27} = 2\sqrt{27} \] - The area \(A\) of a circle is given by the formula \(A = \pi r^2\). - Given \(r^2 = 108\), the area \(A\) is: \[ A = \pi \times 108 = 108\pi \] Therefore: - **Center:** \((-7, -2)\) - **Area:** \(108\pi\) square units. Note: This transcription would be formatted to match the educational website's style guide, including appropriate spacing and formatting for clarity.
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