[tex] \sin {}^{2} ( \alpha ) + \cos {}^{2} ( \alpha ) = 1 \\ \cos( \alpha ) = \sqrt{(1 - \sin {}^{2} ( \alpha ) } = + - \sqrt{(1 - \frac{9}{25} )} = + - \sqrt{ \frac{16}{25} } \\ \cos( \alpha ) = - \frac{4}{5} \\ \tan( \alpha ) = \frac{ \sin( \alpha ) }{ \cos( \alpha ) } = \frac{3}{5} \times ( - \frac{5}{4} ) = - \frac{3}{4} [/tex]
Sper ca te-am ajutat
