Equation solving help :(

I have three circumferences and I know there is a piont
where the three circles intersec themselves.

so if a circle with centre P(a,b) and radius R
then its equation is:

(X-a)^2+(Y-b)^2=R^2

so I need to find a X,Y that satisfy the 3 equations at
the same time.

So:

X= (...?...)
Y= (...?...)


Help really appreciated :)

Thanks!
Paolo

Circle with center (a,b):
------------------------
X=cos(Alpha)*R+a
Y=sin(Alpha)*R+b
Alpha=tan-1(Y/X)=sin-1(Y/R)=cos-1(X/R)

thanks Ed :)
will give that a try...

Paolo.