One corner of a cube is cut off, creating a new triangular face, as shown.
How many edges does this new solid have?
, 2015
Pick one
Solution
The original cube (before the corner was cut off) had 12 edges.
Cutting off the corner does not eliminate any of the 12 edges of the original cube.
However, cutting off the corner does add 3 edges that were not present originally, the 3 edges of the new triangular face. Since no edges of the original cube were lost, but 3 new edges were created, then the new solid has edges.
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