Which pattern describes alternate interior angles formed by two lines and a transversal?

• A. Z pattern
• B. C pattern
• C. V pattern
• D. X pattern

Answer: (A)

Alternate interior angles form a Z-shaped pattern when a transversal crosses two lines. Look inside the region between the lines and pick the pair of angles that lie on opposite sides of the transversal. Those two angles line up to make a Z as you move along the transversal from one intersection to the other. When the lines are parallel, those alternate interior angles are equal, which is why this pattern is especially important for solving and proving things about parallel lines. So the description that matches this situation is the Z pattern. If you think about other patterns, angles on the same side of the transversal form a C pattern and are supplementary, while vertical angles create an X shape at each intersection.