Explicație pas cu pas:
[tex]\tan(OBC) = \frac{OC}{OB} = \frac{3}{ - 6} = - \frac{1}{2} [/tex]
[tex]\tan(OAD) = \frac{OD}{OA} = \frac{ - 2}{4} = - \frac{1}{2} [/tex]
[tex]\tan(OBC) = \tan(OAD) \\ => AD || BC[/tex]
sau
[tex]AD: \: \: m = \frac{ - 2 - 0}{0 - 4} = \frac{1}{2} \: \: \: \: \\ BC: \: \: m = \frac{ 3 - 0}{0 - ( - 6)} = \frac{1}{2}[/tex]