If $P$ is any point on the ellipse $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$ and not lying on axes, whose foci are ${\mathrm{S}}_1\mathrm{and} {\mathrm{S}}_2$$.\text{ Let }\mathrm{\angle }{\mathrm{PS}}_2{\mathrm{S}}_1=\alpha \text{ and }\mathrm{\angle }{\mathrm{PS}}_2{\mathrm{S}}_1=\beta$ then which of the following option(s) must be correct? $(a,b>0)$