Answer: 10 + 10.47.
- A 10 + 10.47
- B 10 + 5.24
- C 5 + 10.47
- D 5 + 5.24
Correct answer: A. 10 + 10.47
Explanation: Perimeter = 2r + arc = 2×5 + (120/360)×2π×5 = 10 + (1/3)×10π = 10 + 10.47 ≈ 20.47.
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