And yet, with 'solve', these two versions appear equivalent.
2010a:
tic, [x,y]=solve('x^2+y^2=4','(x-1)^2+(y-1)^2=1'), toc
x =
7^(1/2)/4 + 5/4
5/4 - 7^(1/2)/4
y =
5/4 - 7^(1/2)/4
7^(1/2)/4 + 5/4
Elapsed time is 0.065465 seconds.
2012b:
tic, [x,y]=solve('x^2+y^2=4','(x-1)^2+(y-1)^2=1'), toc
x =
7^(1/2)/4 + 5/4
5/4 - 7^(1/2)/4
y =
5/4 - 7^(1/2)/4
7^(1/2)/4 + 5/4
Elapsed time is 0.066874 seconds.