Alternate Interior Angles
Definition of Alternate Interior Angles
Alternate interior angles are two congruent interior angles that lie on different parallel lines and on opposite sides of a transversal.
Examples of Alternate Interior Angles
In the figure shown, l is the transversal that cut the parallel lines. Angles a and d and angles b and c are alternate interior angles.
Video Examples: Alternate Interior Angles
Solved Example on Alternate Interior Angles
Ques: Find the measure of angle m in the figure shown.
D. Insufficient information
Correct Answer: C
Step 1: 120° + n = 180° [Straight angle.]
Step 2: n = 60° [Solve for n.]
Step 3: n = 60° implies m = 60°, because m and n are alternate interior angles and so they are congruent.