# Geometry Help!? 10 points! Which figure is not completely constructed from polygons?

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Which figure is not completely constructed from polygons?

A. tetrahedron

B. pyramid

C. cylinder

D. cube

• cylinder

• Cylinder.

Polygons are basically two dimensional objects made up of straight lines.

Although a circle is also a two dimensional object, it is made up of a “curved” line as opposed to a straight one.

Hence, since the cylinder has two circles it is the only one not completely made up of polygons.

• Polygons are composed of a finite sequence of straight line segments.

The cylinder does not, it has two circles (not polygons). You may say that could unwrap the lateral side into a rectangle.

The others have triangles, and/or squares, which are polygons.

• C. Cylinder—>not formed from polygons

• A cylinder. The faces are circles which are not polygons.

• Cylinder is not a polygon because it has no straight sides

• C. Cylinder, because its curved face is not a polygon. Note that the curved face can be unfolded into a rectangle, but it requires that you artificially introduce an edge that is not present in the solid figure.

• A cylinder because it has no sides.