\( \frac{x*y}{x^2+y^2} \)=c|*(x^2+y^2)
c*x^2+c*y^2=x*y|- c *x^2-x*y
c*y^2-x*y=- c *x^2|:c
y^2-\( \frac{xy}{c} \) =-x^2
(y-\( \frac{x}{2c} \))^2=-x^2+\( \frac{x^2}{4c^2} \)|\( \sqrt{} \)
1.)y-\( \frac{x}{2c} \)=...
y₁=\( \frac{x}{2c} \)+...
y₂=\( \frac{x}{2c} \)-...