SOLUTION: Given the circle: (y+7)^2+(x-4)^2=18 Find the center: Find the exact radius: Can someone show me what formulas to use, and how to use them? Thank You!!

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Question 60213: Given the circle: (y+7)^2+(x-4)^2=18
Find the center:
Find the exact radius:
Can someone show me what formulas to use, and how to use them?
Thank You!!
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
Given the circle: (y+7)^2+(x-4)^2=18
Find the center: (4,-7)
Find the exact radius: 3sqrt%282%29
:
The standard form of the equation of a line is highlight%28%28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2%29, Where the center is (h,k) and the radius is r.
Your equation is a little out of order and I initially put down the wrong answer for the center because I didn't notice.
(x-4)^2+(y+7)^2=18
The center is:
%28x-highlight%284%29%29%5E2%2B%28y-highlight%28-7%29%29%5E2=18 (h,k)=(4,-7)
The radius is:
%28x-4%29%5E2%2B%28y%2B7%29%5E2=highlight%2818%29
r%5E2=18
r=sqrt%2818%29
r=sqrt%289%29%2Asqrt%282%29
r=3%2Asqrt%282%29
Happy Calculating!!!