Question

a expressão cos x +sen x . tg x /cos x vale :

Answer 1

$\frac{cosx +senx.tgx}{cosx}= \frac{cosx+senx* \frac{senx}{cosx} }{cosx} = \frac{ \frac{cos^2x+sen^2x}{cosx} }{cosx}= \frac{1}{cos^2x} =sec^2x$