three students attempt to define what it means for \overleftrightarrow{ab} ab a, b, with, \overleftrightarrow, on top and \overleftrightarrow{cd} cd c, d, with, \overleftrightarrow, on top to be perpendicular. \qquad 2 lines intersecting. one line is vertical with points a and b on opposite ends. the other line is horzontal with points c and d on opposite ends. they intersect at point o in the middle of both lines. can you match the teacher's comments to the definitions?