Which pattern describes same-side interior angles formed by two lines and a transversal?

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

Answer: (B)

Same-side interior angles are the two angles that lie between the two lines and on the same side of the transversal. If you shade or connect those interior angles on one side, their positions trace out a shape that looks like a curved letter C around the transversal. That visual cue is why the pattern is described as the C pattern. This stands in contrast to the Z pattern, which shows alternate interior angles on opposite sides of the transversal and forms a Z shape. So the two interior angles on the same side naturally form the C pattern. (If the lines are parallel, those same-side interior angles sum to 180 degrees.)