These lessons, with videos, examples, solutions and worksheets help Grade 8 students learn about co-interior angles (also called consecutive interior angles, same side interior angles).

**Related Pages**

Alternate Interior Angles

Corresponding Angles

More Lessons for Grade 8

Math Worksheets

**What is the Consecutive Interior Angles Theorem?**

The Consecutive Interior Angles Theorem states that if two parallel lines are cut by a transversal,
then consecutive interior angles are supplementary (= 180°).

**What is the Alternate Interior Angles Theorem?**

The Consecutive Interior Angles Theorem states that if two parallel lines are cut by a transversal,
then each pair of alternate interior angles is congruent.

The following figures give the some examples of co-interior angles. Scroll down the page for more examples and solutions.

**How to use the Consecutive Interior Angles Theorem?**

Parallel lines : Alternate Interior, Corresponding and Co-interior angles

Parallel Lines and Interior Angles

Relationships between Parallel Lines and Interior Angles

Parallel Lines and Transversal

Helps describe the angle pairs formed by parallel lines and a transversal. Looks at corresponding,
alternate interior and same side interior angles

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