# equation of a circle

• Jul 17th 2007, 07:10 PM
sanee66
equation of a circle
equation of a circle and put it with a number that can be added to both sides of the equation in order to change the equation to a sum of two complete squares.

x2+y2+18x+4y=19 85
x2+18x+y2+4y=19

Is this good? where do I go from here?
• Jul 17th 2007, 09:25 PM
CaptainBlack
Quote:

Originally Posted by sanee66
equation of a circle and put it with a number that can be added to both sides of the equation in order to change the equation to a sum of two complete squares.

x2+y2+18x+4y=19 85
x2+18x+y2+4y=19

Is this good? where do I go from here?

It wants you to write the equation in the form:

$(x-a)^2+(y-b)^2=r^2$

where $a,\ b$ and $r$ are numbers determined by the coefficients and constant in the original equation.

RonL