1. ## finding radius/center of circle

find the radius r and the center (h,k) of the following circle
2 2
3 (x-3) + 3y =75

2. Originally Posted by shawn9356
find the radius r and the center (h,k) of the following circle
2 2
3 (x-3) + 3y =75
do you mean $\displaystyle 3(x - 3)^2 + 3y^2 = 75$?

if so, note that this is: $\displaystyle (x - 3)^2 + y^2 = 5^2$

Now, when a circle is written in the form $\displaystyle (x - h)^2 + (y - k)^2 = r^2$, the center is $\displaystyle (h,k)$ and the radius is $\displaystyle r$. i leave the rest to you

3. Hi !

Originally Posted by shawn9356
find the radius r and the center (h,k) of the following circle
2 2
3 (x-3) + 3y =75
Use ^2 to write exponents

You know that the equation of a circle, of center $\displaystyle O(x_O ~,~y_O)$ and of radius R is :

$\displaystyle (x-x_O)^2+(y-y_O)^2=R^2$

Therefore, try to make appear that form.

The reflex will be to divide the whole equation you have by 3, in order to get $\displaystyle (x-3)^2+y^2=\dots$

Then, note that $\displaystyle y=y-0$.
Recognize in your equation $\displaystyle x_O, y_O$ and R