The curved surface area of a right circular cone is $150\pi {\text{cm}}^2$. If its slant height is $15\text{cm}$, find the radius of its base.

Step-by-step solution

1. Curved surface area of a cone = $\pi rl$, where $l$ is slant height.
2. Set $\pi rl=150\pi$.
3. Cancel $\pi$ from both sides: $rl=150$.
4. Substitute $l=15$: $r\times 15=150$.
5. Solve for $r$: $r=150/15=10$ cm.
6. Hence the correct option is (c) $10\text{cm}$.

Concept tested: Curved surface area of a cone

Published 21 August 2026 · How this solution was prepared and checked

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