Question

what does the following notation describe? $overleftrightarrow{ab}perpoverleftrightarrow{dc}$ two perpendicular segments two congruent lines two perpendicular lines

Explanation:

The symbol $\perp$ in geometry represents perpendicularity. The notation $\overleftrightarrow{AB}\perp\overleftrightarrow{DC}$ indicates that the line containing points A and B is perpendicular to the line containing points D and C.

Answer:

two perpendicular lines