a. \(d//d_1\Leftrightarrow\left\{{}\begin{matrix}-2=1-m\\m\ne2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m=3\\m\ne2\end{matrix}\right.\)
b. \(d\cap d_1\Leftrightarrow-2\ne1-m\Leftrightarrow m\ne3\)
c. \(d=d_1\Leftrightarrow\left\{{}\begin{matrix}-2=1-m\\m=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m=3\\m=2\end{matrix}\right.\)
\(1,\Leftrightarrow\left\{{}\begin{matrix}-2=1-m\\m\ne2\end{matrix}\right.\Leftrightarrow m=3\\ 2,\Leftrightarrow\left\{{}\begin{matrix}-2\ne1-m\\m\ne2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m\ne3\\m\ne2\end{matrix}\right.\\ 3,\Leftrightarrow\left\{{}\begin{matrix}-2=1-m\\m=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m=3\\m=2\end{matrix}\right.\Leftrightarrow m\in\varnothing\)