To identify which shapes cannot be a cross section of a cube, we first need to understand that a cross section of a cube is formed when a plane intersects the cube.
A cube can have the following cross sections:
- A triangle can be formed if the plane intersects three edges of the cube.
- A rectangle can be formed when the plane cuts parallel to one pair of opposite faces.
- A trapezoid can occur from an oblique cut.
- A square can also be a cross section if the plane is parallel to a face.
However:
- A heptagon (7 sides) and an octagon (8 sides) cannot be formed as a cross section of a cube because any cross section of a cube will have at most 4 sides. Any plane that cuts through a cube will create polygons with up to 4 edges (like triangles, rectangles, trapezoids, or squares).
Therefore, the two shapes that cannot be a cross section of a cube are:
- B. heptagon
- C. octagon