PROVING LINES PARALLEL

CONVERSE OF

… Corresponding Angles Postulate: If the pairs of corresponding angles are congruent, then the lines are parallel

If Angle 2 is congruent to angle 6 then then L

is parallel to M.

The same is true for any other pair of

Corresponding angles.

CONVERSE OF

…Alt. Interior Angles Theorem: If the pairs of ALT. Interior angles are congruent, then the lines are parallel

If angle 3 is congruent to angle 6 or angle 4 is

Congruent to angle 5, then the lines

are parallel.

CONVERSE OF

…Alt. Exterior Angles Theorem: If the pairs of ALT. Exterior angles are congruent, then the lines are parallel

If angle 1 is congruent to angle 8 or

angle 2 congruent to angle 7, then

the lines are parallel

CONVERSE OF

…Same Side Interior Theorem: If the pairs of same side interior angles are supplementary, then the line are parallel

If angle 3 + angle 5 = 180 or

angle 4 + angle 6 = 180 then

the line are parallel.

EXAMPLE 1

EXAMPLE 2

EXAMPLE 3