Mensurationhard · Past Paper
The total surface area of a right circular cylinder is 231 cm². If its curved surface area is two-thirds of its total surface area, find the radius.
A3.5 cm
B7 cm
C10.5 cm
D2.1 cm
✓ Correct Answer: A — 3.5 cm
TSA = 231. CSA = 2/3 * 231 = 154. 2 * Base Area = TSA - CSA = 231 - 154 = 77. πr² = 77/2 = 38.5. r = 3.5 cm.
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