SOLUTION: Dear Sir/Madam, I am confronted with the following problem: "Find the center and radius of the circle with the following equation: x^2 + y^2

SOLUTION: Dear Sir/Madam, I am confronted with the following problem: "Find the center and radius of the circle with the following equation: x^2 + y^2 - 10x + 8y -40 = 0" I have

Question 6644: Dear Sir/Madam,
I am confronted with the following problem:
"Find the center and radius of the circle with the following equation:
x^2 + y^2 - 10x + 8y -40 = 0"
I have absolutely no idea how to approach this question. I want to use the x^2 + y^2 = r^2 formula, but I don't how to integrate that into this problem. Can you please help me?
Thanks in advance.
Regards,
-Mike
Answer by rapaljer(4671) (Show Source): You can put this solution on YOUR website!
This is a completing the square problem:

Get the x terms together, and the y terms together, and leave a space after each to complete the square. Also add + 40 to each side of the equation:

For the first blank, take half of the 10, which is 5 and square to get 25.
For the second blank, take half of the 8, which is 4 and square to get 16. Add these to both sides of the equation:

Therefore this is a circle whose center is at (5, -4) and so .

R^2 at SCC

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