GATE 2024 CE (CE2) – Question 10
Visualize a cube that is held with one of the four body diagonals aligned to the vertical axis. Rotate the cube about this axis such that its view remains unchanged. The magnitude of the minimum angle of rotation is
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Correct answer: (A) 120°
Explanation
Looking along a body diagonal, a cube has a 3-fold rotational symmetry: the three faces around the vertex and the three edges look the same after a turn of $\frac{360°}{3} = 120°$. (A 60° turn would give the mirror-like hexagon only if the opposite vertices were swapped, which a rotation does not do.)