Question

which of the following transformations carry the isosceles trapezoid onto itself?rotation of 180° counterclockwiserotation of 90° counterclockwiserotation of 270° counterclockwisereflection across $l$

Explanation:

An isosceles trapezoid has symmetry only about its vertical axis of symmetry (line \( l \)). A 180°, 90°, or 270° counterclockwise rotation would not map the trapezoid onto itself, as it would flip the orientation of the bases and legs incorrectly. Only reflection across its axis of symmetry \( l \) aligns all corresponding sides and vertices perfectly.

Answer:

reflection across \( l \)