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12 votes
The circle below is centered at (4,-1) and has a radius of 3. What is it’s equation?

User Matthew Trout
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1 Answer

9 votes
9 votes

Answer:

(x - 4)^2 + (y + 1)^2=9

Explanation:

The equation of a circle can be written using a kinda of fill-in-the-blank method if you know the coordinates of the center and the radius.

If the center is (h,k) and the radius is r, then fill in those given numbers into:

(x-h)^2 + (y-k)^2 =r^2

The center of your circle is (4, -1).

Fill in 4 for the h, -1 for the k and 3 for the r.

(x-4)^2+(y- -1)^2= 3^2

Simplify.

(x-4)^2+(y+1)^2=9

User Zkwentz
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