Posted by **Beth** on Friday, June 12, 2009 at 4:41pm.

State the center and the radius of the circle represented by the equation

(x + 1)^2 + (y – 5)^2 = 64

- Algebra -
**Reiny**, Friday, June 12, 2009 at 4:50pm
in the general equation of a circle

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

the centre is (h,k) and the radius is r

can you match this with your given equation?

- Algebra -
**Beth**, Friday, June 12, 2009 at 5:22pm
ok based on that I would say the radius is 8 cause 8*8 = 64 and the center is (1,5)? Or do the signs change because of the equation

(x-h)^2 + (y-k)^2 = r^2 making the center (-1,5)?

- Algebra -
**Reiny**, Friday, June 12, 2009 at 5:27pm
radius is correct,

the centre is (-1,5)

- Algebra -
**Beth**, Friday, June 12, 2009 at 5:29pm
That is what I thought, so the standard form would be

(x-(-1]^2 + (y-5)^2 = 64

- Algebra -
**Reiny**, Friday, June 12, 2009 at 5:34pm
yes,

I just mentally change the sign I see in the bracket

- Algebra -
**Beth**, Friday, June 12, 2009 at 5:37pm
Great! Thanks for the help! So R= 8 and the center is (-1,5) got it! Thanks again!

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