$a) d_2 :\frac{x-1}{2}=\frac{y+3}{-2} \Leftrightarrow -x+1=y+3\Leftrightarrow x+y+2=0$
Vì : $\frac{4}{1} \neq \frac{-10}{1} \Rightarrow d_1$ cắt $d_2$
$b) d_2:x-5=\frac{y-3}{2} \Leftrightarrow 2x-y-7=0$
Vì $\frac{12}{2} =\frac{-6}{-1} \neq \frac{10}{-7} \Rightarrow d_1//d_2$
$c) d_2:\frac{x+6}{5} =\frac{y-6}{-4} \Leftrightarrow 4x+5y-6=0$
Vì $\frac{8}{4} =\frac{10}{5} =\frac{-12}{-2} =2\Rightarrow d_1\equiv d_2$