$$\sec ( \theta )=13/12$$
$\theta =2\pi n_{1}+\arctan(\frac{5}{12})\text{, }n_{1}\in \mathrm{Z}$
$\theta =2\pi n_{2}+2\pi -\arctan(\frac{5}{12})\text{, }n_{2}\in \mathrm{Z}$
$\theta =2\pi n_{1}+\arccos(\frac{12}{13})\text{, }n_{1}\in \mathrm{Z}$
$\theta =2\pi n_{2}+2\pi -\arccos(\frac{12}{13})\text{, }n_{2}\in \mathrm{Z}$