• Jun 4th 2008, 12:31 PM
shawn9356
find the radius r and the center (h,k) of the following circle
2 2
3 (x-3) + 3y =75
• Jun 4th 2008, 12:49 PM
Jhevon
Quote:

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
• Jun 4th 2008, 12:51 PM
Moo
Hi !

Quote:

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 :)