Question

alguien me puede demostrar esto$\frac{sen \alpha -cos \alpha }{tan \alpha -1} =cos \alpha$

Answer 1

${\frac{senA-cosA}{tanA-1}=}\\\\{\frac{senA-cosA}{\frac{senA}{cosA}-1}}=}\\\\{\frac{senA-cosA}{\frac{senA-cosA}{cosA}}=}\\\\{\frac{senA-cosA}{1} \times \frac{cosA}{senA-cosA}}=}\\\\{\boxed{cosA}}\\\\{\text{salu2.!! :)}}$