Parallel lines are indicated by arrows going in the same direction. Parallel lines are indicated by arrows going in the same direction. If there is more than one set of parallel lines in a diagram, ...

Why not see how much you know about this topic already? Then work through the page and see if you can beat your score. Parallel lines are the same distance apart from each other all the way along ...

Certain packing and covering problems associated with the common partial transversals of two families $\mathcal{U}$ and $\mathcal{B}$ of subsets of a set $E$ are ...