Answer: πrl.
- A πrl
- B 2πrl
- C πr²
- D πr(r+l)
Correct answer: A. πrl
Explanation: CSA of cone = πrl. Total SA = πrl + πr² = πr(l+r).
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