Yahoo Answers: Answers and Comments for Write the equation of the circle with the center at (1, 1) that passes through the point (1,2)? [Homework Help]
Copyright © Yahoo! Inc. All rights reserved.
https://answers.yahoo.com/question/index?qid=20180922184652AAGfzyP
From Anonymous
enUS
Sat, 22 Sep 2018 18:46:52 +0000
3
Yahoo Answers: Answers and Comments for Write the equation of the circle with the center at (1, 1) that passes through the point (1,2)? [Homework Help]
292
38
https://answers.yahoo.com/question/index?qid=20180922184652AAGfzyP
https://s.yimg.com/zz/combo?images/emaillogous.png

From Michael: The general equation for a circle is
(x  h)² ...
https://answers.yahoo.com/question/index?qid=20180922184652AAGfzyP
https://answers.yahoo.com/question/index?qid=20180922184652AAGfzyP
Sat, 22 Sep 2018 19:18:04 +0000
The general equation for a circle is
(x  h)² + (y  k)² = r²
Where (h, k) is the center of the circle and r is the radius
Using (1, 1) as (h, k)
(x  1)² + (y + 1)² = r²
Point (1, 2) must be on the circumference for the circle to pass through it
Therefor the distance from the center to the point is the radius
Use the distance formula
r² = d² = (x₂  x₁)² + (y₂  y₁)²
r² = (1  1)² + (2  1)²
r² = 0 + 9
r² = 9
The equation of the circle is
(x  1)² + (y + 1)² = 9 <––––––