Panta dreptei BC : m=[tex] \frac{ y_{C}- y_{B} }{ x_{C} - x_{B} }= \frac{2+2}{4+4}= \frac{1}{2} [/tex], panta perpendiculare m'=[tex]- \frac{1}{m}=-2 [/tex].
ecuatia dreptei ce trece prin A si are panta m' este: [tex]y- y_{A}=m'(x- x_{A}),deci,y-2=-2(x+2),sau,2x+y+2=0 [/tex]