Which one of the options best describes the transformation of the…
2023
Which one of the options best describes the transformation of the 2-dimensional figure P to Q, and then to R, as shown?

- A.
Operation 1: A clockwise rotation by 90º about an axis perpendicular to the plane of the figure
Operation 2: A reflection along a horizontal line
- B.
Operation 1: A counter clockwise rotation by 90º about an axis perpendicular to the plane of the figure
Operation 2: A reflection along a horizontal line
- C.
Operation 1: A clockwise rotation by 90º about an axis perpendicular to the plane of the figure
Operation 2: A reflection along a vertical line
- D.
Operation 1: A counter clockwise rotation by 180º about an axis perpendicular to the plane of the figure
Operation 2: A reflection along a vertical line
Attempted by 114 students.
Show answer & explanation
Correct answer: A
Key observation: follow a single distinctive spike (a prominent point) on the star to see how it moves through each operation.
Step 1 — Rotation: Rotate the original figure by 90 degrees clockwise about the axis perpendicular to the plane. After this rotation, the tracked spike moves from its position in the original figure to the position shown in the intermediate figure. This orientation matches Q.
Step 2 — Reflection: Reflect the rotated figure across a horizontal line (flip top to bottom). This moves the tracked spike from its place in Q to the final position found in R. The flipped top/bottom orientation matches R exactly.
Why the other transformation choices fail:
Using a counterclockwise 90° rotation moves the spike the wrong way and will not match the intermediate figure.
Reflecting across a vertical line (left/right flip) instead of a horizontal line would place the spike on the wrong side and not produce R.
A 180° rotation changes the star's orientation much more than the intermediate Q, so the intermediate figure cannot result from a 180° rotation.
Conclusion: The correct sequence is a 90° clockwise rotation followed by a reflection across a horizontal line.