## Precalculus (6th Edition) Blitzer

This statement makes sense because the equation gives $A=C=0, B=2$. Thus $cot2\theta=\frac{A-C}{B}=0$ and $\theta=45^\circ$ which gives the rotation angle. Also, as $B^2-4AC=4\gt0$, we can identify the equation as a hyperbola.