Cross-Sections of 3D Figures Math Example 3
Follow the full solution, then compare it with the other examples linked below.
Example 3
hardA regular hexagonal prism is cut by a plane perpendicular to its bases that passes through two opposite edges. What is the shape of the cross-section?
Solution
- 1 Step 1: A regular hexagonal prism has two parallel regular hexagon bases connected by rectangular lateral faces. The plane is perpendicular to both bases (vertical cut).
- 2 Step 2: The plane passes through two opposite edges of each hexagonal base. In a regular hexagon, opposite edges are parallel and separated by a distance equal to (where is the side length). The plane intersects the top base along a segment connecting two opposite edges and the bottom base along a corresponding segment.
- 3 Step 3: Since the cutting plane is perpendicular to the bases, the cross-section has two horizontal edges (one on each base) and two vertical edges (along the lateral faces). The top and bottom edges have equal length, and the vertical edges equal the prism's height .
- 4 Step 4: The cross-section is a rectangle with width equal to the distance between opposite edges of the hexagon () and height equal to .
Answer
The cross-section is a rectangle with dimensions .
When a plane cuts a prism perpendicular to its bases and passes through two opposite edges, it slices through corresponding points on both bases symmetrically. Since the top and bottom intersections are congruent and the lateral edges are vertical, the resulting cross-section is always a rectangle.
About Cross-Sections of 3D Figures
A cross-section is the flat, two-dimensional shape revealed when a plane cuts through a three-dimensional solid. For example, slicing a cylinder parallel to its base gives a circle, while slicing it at an angle gives an ellipse.
Learn more about Cross-Sections of 3D Figures โMore Cross-Sections of 3D Figures Examples
Example 1 easy
A horizontal plane cuts through the middle of a right circular cone (parallel to the base). What 2D
Example 2 mediumIdentify and describe the cross-sections formed when a plane cuts a cube in the following ways: (a)
Example 4 easyA plane cuts through a sphere. What shape is the cross-section, and when is it the largest possible
Example 5 hardA rectangular prism (box) has dimensions [formula] cm [formula] cm [formula] cm. A plane cuts throug