"Let $G \cong H$. In this case $G$ is planar graph $\Leftrightarrow$ $H$ is planar graph." If this proposition true, prove that. If false, give an example.
This question in my exercise book. I curious solve of this quesiton. I know if a graph is planar that graph edge's don't intersect. But I can't explain clearly this proof. Can you help me? Thank you. (My english is not good, if I said wrong something sorry for that)