Answer: 5 cm.
- A 4 cm
- B 5 cm
- C 7 cm
- D 6 cm
Correct answer: B. 5 cm
Explanation: The perpendicular from centre bisects the chord. Half-chord = 4. r² = 4² + 3² = 16 + 9 = 25. r = 5 cm.
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