Question

considerando as retas (r)4x+3y-8=0 e (s)x+7y-27=0 e determine a medida do angulo formado entre elas

Answer 1

$tan \theta=| \frac{m_r-m_s}{1+m_r.m_s} |$
A reta $r:4x+3y-8=0 \\ m_r=-4/3 \\ s: x+7y-27=0 \\ m_s=-1/7$
$tan \theta=| \frac{-4/3+1/7}{1+4/3.1/7}|=| \frac{-25/21}{25/21}|=1$
$\theta=45\º$