Question

find the equation of a circle with a center at (-1,2) and one point on the circle is at (2,-1)

Answer 1

I'm not very good at this sort of stuff, but since I see that no one else has been helping...
equation of circle = (x-h)^2 + (y-k)^2 = r^2
when center is point (h, k)
and radius = r

Answer 2

so let h = -1
and k = 2

and find the distance between the points (-1, 2) and (2, -1)

Answer 3

thank you guys! :)
seriously appreciate it a lot.

Answer 4

glad we could help :)

Answer 5

yes! it is correct so far! :)

then you would find the distance between points (-1,2) and (2,-1)
to get r

\[distance formula: \sqrt{(x _{2}-x _{1})^{2} + (y _{2}-y _{1})^{2}} \]

Answer 6

okay, last question. lol which numbers are x1 and x2 and y1 and y2?

Answer 7

does the order go (x1,y1) and (x2,y2)

Answer 8

yes!!! :D

Answer 9

hmmm and I suggest leaving it in square root form

Answer 10

yes :)

so r^2 = 18

Answer 11

so is that my completed answer? :D

Answer 12

it was asking for the equation
so could you write it out so we can make sure? :)

Answer 13

like that? ^

Answer 14

yes, but they want
(x-h)^2 + (y-k)^2 = r^2

so now that you have ^^ r^2 = 18 ...

Answer 15

i need to find x

Answer 16

mmm not quite?

before you had gotten
(x+1)^2 + (y-2)^2 = r^2

then all you have to do is plug in 18 for r^2

Answer 17

so (x+1)^2 + (y-2)^2= 18

Answer 18

correct! :D

Answer 19

wow, thank you so much!!!! i really wish I could repay you someway.

Answer 20

If you appreciate someone's help, you can given them the "Best Response" medal ^_^

Answer 21

oh, haha. thanks. if you couldnt tell im new to the site.

Answer 22

lol I could tell :P
btw Welcome to OpenStudy! <3

Answer 23

thanks! :D

Answer 24

if you need anymore help, you can tag people by putting a @ in front of their username
also, if you would like to know more, there is a tutorial video :)
https://www.youtube.com/watch?v=lDiiH8PItto

Answer 25

wow, great! haha
thanks again. see ya around!