Cho góc \(\alpha \) thỏa mãn \(\sin \alpha = \frac{3}{5}\) và \({90^^\circ } < \alpha < {180^^\circ }\). a) \(\cos \alpha > 0\).

\(\cos \alpha > 0\).

\(\cos \alpha = - \frac{4}{5}\).

\[\tan ({180^\circ } - \alpha ) = - \frac{3}{4}\].

\[P = \frac{{\tan \alpha - \cos \left( {{{90}^\circ } - \alpha } \right).\sin \alpha }}{{\sin \left( {{{90}^\circ } - \alpha } \right).\sin \left( {{{180}^\circ } - \alpha } \right)}} = \frac{{37}}{{16}}\].