Angle Relationships

A guide to the angle relationships formed when two parallel lines are intersected by a transversal.

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Corresponding Angles

Rule: The angles are congruent (equal).

Examples: (∠1, ∠5), (∠2, ∠6), (∠3, ∠7), (∠4, ∠8)

1 5

Alternate Interior Angles

Rule: The angles are congruent (equal).

Examples: (∠3, ∠6), (∠4, ∠5)

3 6

Alternate Exterior Angles

Rule: The angles are congruent (equal).

Examples: (∠1, ∠8), (∠2, ∠7)

1 8

Consecutive Interior Angles
(Same-Side Angles)

Rule: The angles are supplementary (add up to 180°).

Examples: (∠3, ∠5), (∠4, ∠6)

3 5

Vertical Angles

Rule: The angles are congruent (equal).

Examples: (∠1, ∠4), (∠2, ∠3), (∠5, ∠8), (∠6, ∠7)

1 4

Linear Pair

Rule: The angles are supplementary (add up to 180°).

Examples: (∠1, ∠2), (∠3, ∠4), (∠5, ∠6), (∠7, ∠8)

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