Question 81
For what real numbers $r$ does the system of equations
$$
\left\{\begin{aligned}
x^{2} &= y^{2} \\
(x - r)^{2} + y^{2} &= 1
\end{aligned}\right.
$$
have no solutions?
$$
\left\{\begin{aligned}
x^{2} &= y^{2} \\
(x - r)^{2} + y^{2} &= 1
\end{aligned}\right.
$$
have no solutions?