SOL006 · 3D solids & mensuration · Classes 9–12
Cone
A circular base joined to a single point (apex).
Cone📐 Formula
Slant l = √(r² + h²); Volume = ⅓πr²h; Curved SA = πrl; Total SA = πr(l + r)
✏️ Worked example
r = 3, h = 4: l = 5; V = 12π ≈ 37.70; CSA = 15π ≈ 47.12; TSA = 24π ≈ 75.40.
🌍 Where it is used
Ice-cream cones, funnels and traffic cones.
❓ Quick check
A cone holds what fraction of a cylinder with the same base and height?