Parallel Lines and Indirect Proofs

Question 1

Special Angle Pairs

Answer 1

Corresponding

Alternate Interior

Alternate Exterior

Same Side Interior

Same Side Exterior

Question 2

Indirect Proof

Answer 2

Proof by Contradiction

Prove the Contrapositive

Question 3

Given two lines cut by a transversal

Answer 3

alt int angles are congruent

alt ext angles are congruent

corresponding angles are congruent

same side int angles are suppplementary

same side ext angles are supplementary

IFF

the lines are parallel

and

If: two lines are coplanar to each other and perpendicular to a 3rd line

then: the lines are parallel

Question 4

Parallel

Answer 4

Lines that are coplanar and do not intersect

Question 5

Skew

Answer 5

Noncoplanar lines

Question 6

Exterior Angle Inequality Theorem

(Ext Angle ≠ Thm)

Answer 6

The measure of the exterior angle of a triangle is greater than the measure of either remote interior angles