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The curved (lateral) surface area of a cone with base radius r and slant height l is:
Answer & Solution
Correct answer: C.
1. The curved surface unrolls to a sector with radius l and arc length equal to the base circumference 2πr.
2. The sector's area = (1/2) × radius × arc = (1/2)(l)(2πr) = πrl.
3. So the curved surface area equals πrl.
4. πr² is the base area, not the curved surface.
5. (1/3)πr²l would be a volume-like dimension, not an area.
_Source: SCERT Kerala Std X Mathematics Part-2, Chapter 7-8 (pp 180-199, 2019 ed.)._
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