Answer: a/2.
- A a
- B a/2
- C a√2/2
- D a/4
Correct answer: B. a/2
Explanation: Inscribed sphere touches all 6 faces. Diameter = side of cube = a. Radius = a/2.
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