geometry
alternate exterior angles
If a transversal intersects two parallel lines, then alternate exterior angles are congruent.
same side exterior angles
If a transversal intersects two parallel lines, then same-side exterior angles are supplementary.
Congruent Complements Theorem
If two angles are complementary to the same angle (or to congruent angles), then they are congruent.
Right Angle Supplements Theorem
If two angles are congruent and supplementary, then each is a right angle.
Congruent Supplements Theorem
If two angles are supplementary to the same angle (or to congruent angles), then they are congruent
Vertical Angles Theorem
If two angles are vertical angles, then they are congruent.
Converse of the Same-Side Interior Angles Theorem
If two coplanar lines are cut by a transversal so that a pair of same-side interior angles are supplementary, then the two lines are parallel.
converse of alternate exterior angles theorem
If two lines and a transversal form alternate exterior angles that are congruent, then the two lines are parallel.
Converse of the Alternate Interior Angles Theorem
If two lines and a transversal form alternate interior angles that are congruent, then the two lines are parallel.
Converse of the Corresponding Angles Postulate
If two lines and a transversal form corresponding angles that are congruent, then the two lines are parallel.
alternate interior angles
If two parallel lines are cut by a transversal, then the alternate interior angles are congruent.
Corresponding Angles Postulate
If two parallel lines are cut by a transversal, then the pairs of corresponding angles are congruent
same side interior angles
If two parallel lines are cut by a transversal, then the two pairs of same-side interior angles are supplementary. (m<1 + m<2 = 180)
Right Angle Theorem
All right angles are congruent
converse of same exterior angles theorem
if 2 lines and a transversal form same-side ext angles that are supplementary then 2 lines are parallel