Respostas

2014-01-31T01:16:09-02:00
sen b² + cosb²  = 1



(\frac{5}{12})²  + cosb² = 1

cos b² = 1 - (\frac{5}{12}

cos b² = 1 - \frac{25}{144}

cos b ² = \frac{119}{144}

cos b = \frac{ \sqrt{119}}{12}