Loading...
Parallel and Perpendicular Lines
A
B
C
D
E
. . . .

Parallel Lines and Transversals

Theorem. Alternate Exterior Angles Theorem
If two parallel lines are cut by a transversal, then alternate exterior angles are congruent.

Refer to the given figure. If m∥n, then ∠2≅∠7 and ∠1≅∠8. Prove the congruence of the first angle pair and the second pair can be proven similarly.

Given: m∥n cut by transversal t
Prove: ∠2≅∠7

Proof: