Aplane intersects a prism to form a cross section that is a polygon with five sides. what is the minimum number of sides that the polygon at the base of the prism must have?

The answer is 4.

Since the plane is cutting through the prism to make five sides, then the original shape has less than five sides.

Five would work if you just slice across the prism. But, since a prism is a 3D figure, you can't have a prism with a 2-sided base.

A three-sided shape is a triangle, which also can't be cut into a 5 sided prism.

 So, the answer would need to be 4.

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