This document contains geometry problems involving angle pairs, parallel lines, and alternate interior angles. It asks the reader to 1) classify different angle pairs as adjacent, interior, or corresponding, 2) prove lines are parallel using information about equal angles and sides of triangles, 3) find the measures of angles when two lines are parallel and alternate interior angles are equal, and provides the answers.

1. Activity 3 (answer key)
1. Classify the following angle pairs.
a. <1 and <7 ___________AE____________ 2
b. <3 and <5 ___________AI____________ 1
c. <4 and <8 ____________CA___________
d. <2 and <6 _____________CA__________
e. <4 and <6 ____________AI___________
f. <2 and <8 ____________AE___________ 5 6
8 7
2. In the figure, AC = BC and <1 = <B .
Prove that CE // AB . 1
C 2
3
A B
STATEMENTS REASONS

2. 3. Given: ∆ ABC with AC=BC, DC=EC and <1 ≅ <B. C
Prove: DE // AB
D E
A B
STATEMENTS REASONS
4. Given: AB and CD bisect each other at E.
Prove: AD // CB
Hint : Prove first the congruence between the two triangles. Then show that a pair of
alternate interior angle are congruent. C B
E
A D
STATEMENTS REASONS
3 4

3. 5. If AB // DC and AD // BC , what is the measure of the numbered angles?
ANSWERS:
1. 12 A 1
2. 60 120°
3. 120 2 3
4. 120
5. 60
6. 120
4 5) (6