Which angles are formed in a Z pattern when two lines are cut by a transversal?

• A. Alternate interior angles
• B. Same-side interior angles
• C. Vertical angles
• D. Exterior angles

Answer: (A)

When a transversal cuts two lines, the angles inside the region between the lines that lie on opposite sides of the transversal form a Z shape. These are called alternate interior angles. This pattern is described by the Alternate Interior Angles Theorem: if the two lines are parallel, those angles are equal. The other angle pairs don’t form the Z shape: same-side interior angles are inside on the same side of the transversal (they add to 180°), exterior angles are outside the region between the lines, and vertical angles are opposite angles formed at a single intersection. So the Z pattern specifically identifies the alternate interior angles.