Question
A circular sheet of paper is folded along the lines in the directions shown. The paper, after being punched in the final folded state as shown and unfolded in the reverse order of folding, will look like
Official answer and solution
- Official answer
- A
- From
- Official GATE 2021 answer key
Solution
Trace the reverse unfoldings of the paper by applying reflective symmetry across the fold lines.
The circular sheet is first folded in half vertically, then in half horizontally into a quadrant. The corner at the center of the original circle has a sector/circular cut, while the straight edge along the fold receives a rectangular punch.
Unfolding horizontally reflects the shapes across the horizontal axis, and unfolding vertically reflects the shapes across the vertical axis. The central cut expands into a single complete circular hole in the center of the sheet.
The rectangular cutout on the vertical fold creates horizontal rectangles at the top and bottom edges, while reflection across the other axis forms vertical rectangles at the left and right edges. This configuration corresponds exactly to option A.
A
The answer is the one in the official GATE answer key. The solution is this site's own explanation.
Source
- Paper
- GATE 2021 Computer Science and Information Technology (CS, Set-1)
- Question
- 4 of 65, printed as GA Q.4
- Section
- General Aptitude
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