What is the bond line notation for trans-2-butene?
Actually the now-preferred name would be (E)-but-2-ene
The cis-version ((Z)-but-2-ene) would look like:
Since there is no rotation around the double bond, the end-carbons can be either at the same side (Z or cis) or on opposite sides (E or trans).
Here is also a picture of trans-2-butene as a ball-and-stick model
(source for pictures: Wikipedia)