MATHEMATICS

JAMB 2022 - Question 3

Mathematics 2022 JAMB Past Questions - Question 3: A cone has a base radius of 4 cm and a height of 3 cm. The area of its curved surface is

A cone has a base radius of 4 cm and a height of 3 cm. The area of its curved surface is
A:
B:
C:
D:
Examkits App

Examkit's JAMB CBT App

Practice JAMB offline with our Online, PC and Mobile App

  • ✅ 25+ years of past questions (2000 to 2025)
  • ✅ Video solutions and explanation to questions
  • ✅ E-library
  • ✅ Study by topic
  • ✅ And more.

Correct Answer

B

Explanation

To find the area of the curved surface of a cone, we can use the formula:A = πrℓwhere A is the area, r is the radius of the base, and ℓ is the slant height of the cone.In this case, the base radius (r) is given as 4 cm. To find the slant height (ℓ), we can use the Pythagorean theorem:ℓ = √(r^2 + h^2)where h is the height of the cone.Substituting the given values:h = 3 cmr = 4 cmℓ = √(4^2 + 3^2)  = √(16 + 9)  = √25  = 5 cmNow, we can calculate the area of the curved surface:A = π * r * ℓ  = π * 4 cm * 5 cm  = 20π cm^2Therefore, the area of the curved surface of the cone is 20π square centimeters.