Let $P\left(x_{1}, y_{1}\right)$ be a point on the hyperbola $x^{2} / a^{2}-y^{2} / b^{2}=1$
with foci $F_{1}$ and $F_{2}$ and let $\alpha$ and $\beta$ be the angles between
the lines $P F_{1}, P F_{2}$ and the hyperbola as shown in the figure.
Prove that $\alpha=\beta .$ This is the reflection property of the
hyperbola. It shows that light aimed at a focus $F_{2}$ of a hyperbolic mirror is reflected toward the other focus $F_{1 .} .$ .