dy'/(1＋(y')^2)^(3/2)=-dxy'/(1＋(y')^2)^(1/2)=-x+C(y')^2/(1＋(y')^2)=(-x+C)^2(y')^2=1/(1-(x-C)^2)-1y'=(x-C)/((x-C)^2-1)^(1/2)y=((x-C)^2-1)^(1/2)+C2
如图所示：
