Review the information about cross-sections in the Math Notes box for this lesson. Then answer the questions below.  

1. Draw a cube on your paper. Is it possible to slice a cube and get a cross-section that is not a quadrilateral? Explain how.

   Answer (a):

   

2. Barbara has a solid on her desk. If she slices it horizontally at any level, the cross-section is a triangle. If she slices it vertically in any direction, the cross-section is a triangle. What could her shape be? Draw a possible shape.

   Hint (b):

   The base of the solid must be a triangle.

   Answer (b):

   A tetrahedron (a triangle-based pyramid).