Question

(x-1)^2+(y-2)^2=9 how do I find the graphing points for this circle?

Answer 1

The equation of a circle is:
\[(x-h)^2+(y-k)^2=r^2\](h,k) is the center of the circle. Can you find the center?

Answer 2

Thank you Trainwreaking, but could you go into more detail about how to work the problem out? Mathematics is not my strong suit...

Answer 3

and the center would be -1,-2 right?

Answer 4

Not quite. Because the original equation of the circle already has negative signs at (x-h) and (y-k), the 'h' and the 'k' don't get the negatives.
x-h=x-1 and y-k=y-2

Here, you need to solve for the h and the k.
x-h=x-1
-h=-1
h=1

y-k=y-2
-k=-2
k=2

So the center would be at (1,2).

Answer 5

Now, you need to find the other points so that you can actually graph the circle. In the given equation, you are given 9, which is the r^2, the radius squared, in the equation of a circle.
If \[9=r^2\]
can you find the radius?

Answer 6

R=3^2 right?

Answer 7

\[r^2=9\]
So you need to take the square root of both sides.
\[\sqrt{r^2}=\sqrt{9}\]r=√9
r=3

Answer 8

okay, I understand that.