## 3.4 Perpendicular lines

_3-4-1 If two intersecting lines form a linear pair of congruent angles,

then the lines are perpendicular.

3-4-2 (Perpendicular Transversal Theorem)In a plane, if a traversal is perpendicular to one of two parallel lines, then it is

perpendicular to the other line.

3-4-3 If two coplanar lines are perpendicular to the same line, then the two lines are parallel

to each other.

then the lines are perpendicular.

3-4-2 (Perpendicular Transversal Theorem)In a plane, if a traversal is perpendicular to one of two parallel lines, then it is

perpendicular to the other line.

3-4-3 If two coplanar lines are perpendicular to the same line, then the two lines are parallel

to each other.