SOL013 · 3D solids & mensuration · Classes 11–12
Torus
A doughnut shape made by turning a circle (radius r) around an axis at distance R from its centre.
Torus📐 Formula
Volume = 2π²Rr²; Surface area = 4π²Rr
✏️ Worked example
R = 4, r = 1: V = 8π² ≈ 78.96; SA = 16π² ≈ 157.91.
🌍 Where it is used
Tyres, doughnuts, life rings and fusion reactors.
❓ Quick check
Volume of a torus depends on…