Properties of Parallel Lines

A transversal t is a line that intersects two coplanar lines at two distinct points. In the figure below, lines m and n are parallel lines cut by transversal t.

Drag points A, B, C, E, F to change the slopes of lines m, n, and t. Lines m and n will remain parallel.

1. Identify pairs of alternate interior angles.

2. Make a conjecture regarding the alternate interior angles formed when a transversal intersects two parallel lines. Test your conjecture by moving lines m, n, and t and observing the resulting angle measures.

3. Identify pairs of same-side interior angles.

4. Make a conjecture regarding the same-side interior angles formed when a transversal intersects two parallel lines. Test your conjecture by moving lines m, n, and t and observing the resulting angle measures.

5. Identify pairs of corresponding angles.

6. Make a conjecture regarding the corresponding angles formed when a transversal intersects two parallel lines. Test your conjecture by moving lines m, n, and t and observing the resulting angle measures.

7. Identify pairs of alternate exterior angles.

8. Make a conjecture regarding the alternate exterior angles formed when a transversal intersects two parallel lines. Test your conjecture by moving lines m, n, and t and observing the resulting angle measures.

9. Identify pairs of same-side exterior angles.

10. Make a conjecture regarding the same-side exterior angles formed when a transversal intersects two parallel lines. Test your conjecture by moving lines m, n, and t and observing the resulting angle measures.
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Michelle Krummel, April 30, 2010, Created with GeoGebra