passwella.
Menu

WAEC Mathematics 1993 Question 15

Question 15

Mensuration of Solids

Calculate the total surface area of a cone of height 12cm and base radius 5cm. (Take π = 22/7)

  1. A.180 5/7cm2
  2. B.240 2/7cm2
  3. C.235 5/7cm2
  4. D.282 6/7cm2
  5. E.361 3/7cm2
Show the answer and explanation

Answer: D (282 6/7cm2)

Explanation

Slant height l = √(122 + 52) = 13 cm. Total surface area = πr(r + l) = 22/7 × 5 × 18 = 1980/7 = 282 6/7 cm2.