Answer: Every horizontal cross-section at same height has equal area.
- A They have the same total surface area
- B Every horizontal cross-section at same height has equal area
- C They have the same height measured from base to apex
- D They share the same radius at their widest cross-section
Correct answer: B. Every horizontal cross-section at same height has equal area
Explanation: Cavalieri principle: if two solids lying between parallel planes have equal cross-sections at every level, they have equal volumes.
Three standard 3D solids and their key formulas: a cylinder's volume scales with the full height, a cone's volume is exactly one-third of the cylinder with the same base and height, and a sphere's volume and surface area both follow distinct r-based formulas worth memorising separately.
Concept context
Perimeters, areas, and volumes of 2D and 3D shapes