Perpendicular: Two lines, segments, or rays are perpendicular if they intersect to form right angles.

Angles formed by Perpendicular Lines Properties:

If two lines are perpendicular, then they form congruent adjacent angles.

If m n , then 1 2

If two lines form congruent adjacent angles, then the lines are perpendicular.

If 1 2 and 1 adjacent to 2 , then m n