


Description 



Alternate Interior Angles: Alternate interior angles are pairs of angles formed when a third line (a transversal) crosses two other lines. These angles are on opposite sides of the transversal and are in between the other two lines. 
Angles 1,2,3, and 4 are interior angles. Angles 1 and 4 are alternate interior angles. Angles 2 and 3 are also alternate interior angles. Line t (in red) is called a transversal, a line crossing two or more lines. When the transversal cuts through 2 parallel lines, the alternate interior angles formed have a special relationship. Using GSP, what can be said about this relationship between the alternate exterior angles?


