x^2/a^2+y^2/b^2=1(1)y^2/a^2+x^2/b^2=1(2)(1)+(2):(1/a²+1/b²)(x²+y²)=2x²+y²=2/(1/a²+1/b²)所求圆的的方程为：x²+y²=2a²b²/(a²+b²)...