Cone — Base area = 154 cm2 and height = 14 cm. Find the curved surface area (CSA).

Difficulty: Medium

Correct Answer: 154√5 cm2

Explanation:


Introduction / Context:
We are given base area and height. From base area A_b = πr^2, find r, then slant height l = √(r^2 + h^2), and finally CSA = π r l.



Given Data / Assumptions:

  • A_b = 154 cm2 = π r^2
  • h = 14 cm
  • Use π = 22/7


Concept / Approach:
Compute r from r^2 = 154 / π, then l, then CSA symbolically for an exact surd answer.



Step-by-Step Solution:
r^2 = 154 / (22/7) = 49 ⇒ r = 7 cml = √(r^2 + h^2) = √(49 + 196) = √245 = 7√5CSA = π r l = (22/7) * 7 * 7√5 = 154√5 cm2



Verification / Alternative check:
Dimensional check: area units cm2.



Why Other Options Are Wrong:
154√2 cm2 uses wrong sum under root; 11 and 5324 cm2 are invalid magnitudes; 308 cm2 would be π r h or misapplied formula.



Common Pitfalls:
Using height in place of slant height in CSA; not extracting r correctly from base area.



Final Answer:
154√5 cm2

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion