2333.sagews

x1,y1,x2,y2,gSqDist12=var('x1,y1,x2,y2,gSqDist12');

E1=((x1-x2)^2 + (y1-y2)^2 - gSqDist12)^2

diff(E1,x1)

4*(x1 - x2)*((y1 - y2)^2 + (x1 - x2)^2 - gSqDist12)

diff(E1,x2)

-4*(x1 - x2)*((y1 - y2)^2 + (x1 - x2)^2 - gSqDist12)

diff(E1,y1)

4*(y1 - y2)*((y1 - y2)^2 + (x1 - x2)^2 - gSqDist12)

diff(E1,y2)

-4*(y1 - y2)*((y1 - y2)^2 + (x1 - x2)^2 - gSqDist12)