Page 39 - Math Course 2 (Book 2)

Lines and Angles

alternate exterior angles Key Concept
Alternate exterior angles are on opposite sides of
the transversal and outside the parallel lines.
∠A and ∠H Corresponding Parts of Similar Figures

∠B and ∠G
The eight angles formed by parallel lines and a
transversal have special name.
Exterior angles
Line 1 A B • Interior angles lie inside the parallel lines.
C D ∠3, ∠4, ∠5, ∠6

• Exterior angles lie outside the parallel lines.
∠1, ∠2, ∠7, ∠8
Line 2 E F
G H • Alternate interior angle are on opposite sides of
Exterior angles the transversal and inside the parallel lines.
∠3, 5 , 4 and 6
Line 3 : The Transversal
• Alternate exterior angles are on opposite sides of
the transversal and outside the parallel line.
corresponding angles ∠1 and ∠7, and ∠2 and ∠8.
Corresponding angles are in the same position on • Corresponding angles are in the same position
the parallel lines in relation to the transversal.
on the parallel lines in relation to the transversal.
∠1 and ∠5, ∠2 and ∠6, ∠3 and ∠7, ∠4 and ∠8
Line 3 : The Transversal

Line 1 A B transversal
C D
1 2
4 3
Line 2 E F 5 6
G H 8 7

∠B and ∠F
∠C and ∠G Arrowheads are often
used in figures to
∠A and ∠E indicate parallel lines.
∠D and ∠H

Parallel Lines Cut by a Transversal

If two parallel lines are cut by a transversal, then
• corresponding angles are congruent,
• alternate interior angles are congruent, and
• alternate exterior angles are congurent.

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