Solution:
Given:
A square-based pyramid.
- When a pyramid is cut parallel to its base (intersection of a horizontal plane through the pyramid), the cross-section will be the shape of the base.
This can be shown with the various images attached below;
- Also, when a pyramid is cut perpendicular to the base and goes through the top and bottom (intersection of a vertical plane through the vertex point at the top), the cross-section will be a triangle.
This can be shown with the various images attached below;
Therefore,
The intersection of a horizontal plane through this pyramid will result in a square.
The intersection of a vertical plane through the vertex point at the top of the pyramid will result in a triangle.