$$12\ \cot\ \theta=7; 2\cos\ \theta\ \cos\ \theta\ csc\theta$$
$\theta =\pi n_{1}+\arctan(\frac{12}{7})$
$n_{1}\in \mathrm{Z}$
$\theta =\pi n_{1}+\arcsin(\frac{12\sqrt{193}}{193})$
$n_{1}\in \mathrm{Z}$
