$$\cos ALFA=0.25$$
$A=-\sqrt{\frac{2\pi n_{2}+2\pi -\arccos(0.25)}{FL}}\text{, }n_{2}\in \mathrm{Z}\text{, }\left(n_{2}>-1\text{ and }F<0\text{ and }L<0\right)\text{ or }\left(n_{2}>-1\text{ and }L>0\text{ and }F>0\right)\text{ or }\left(n_{2}<0\text{ and }L<0\text{ and }F>0\right)\text{ or }\left(n_{2}<0\text{ and }F<0\text{ and }L>0\right)$
$A=\sqrt{\frac{2\pi n_{2}+2\pi -\arccos(0.25)}{FL}}\text{, }n_{2}\in \mathrm{Z}\text{, }\left(n_{2}>-1\text{ and }F<0\text{ and }L<0\right)\text{ or }\left(n_{2}>-1\text{ and }L>0\text{ and }F>0\right)\text{ or }\left(n_{2}<0\text{ and }L<0\text{ and }F>0\right)\text{ or }\left(n_{2}<0\text{ and }F<0\text{ and }L>0\right)$
$A=-\sqrt{\frac{2\pi n_{1}+\arccos(0.25)}{FL}}\text{, }n_{1}\in \mathrm{Z}\text{, }\left(n_{1}>-1\text{ and }F<0\text{ and }L<0\right)\text{ or }\left(n_{1}>-1\text{ and }L>0\text{ and }F>0\right)\text{ or }\left(n_{1}<0\text{ and }L<0\text{ and }F>0\right)\text{ or }\left(n_{1}<0\text{ and }F<0\text{ and }L>0\right)$
$A=\sqrt{\frac{2\pi n_{1}+\arccos(0.25)}{FL}}\text{, }n_{1}\in \mathrm{Z}\text{, }\left(n_{1}>-1\text{ and }F<0\text{ and }L<0\right)\text{ or }\left(n_{1}>-1\text{ and }L>0\text{ and }F>0\right)\text{ or }\left(n_{1}<0\text{ and }L<0\text{ and }F>0\right)\text{ or }\left(n_{1}<0\text{ and }F<0\text{ and }L>0\right)$
$F=\frac{2\pi n_{1}+\arccos(0.25)}{LA^{2}}\text{, }n_{1}\in \mathrm{Z}$
$F=\frac{2\pi n_{2}+2\pi -\arccos(0.25)}{LA^{2}}\text{, }n_{2}\in \mathrm{Z}$