The radii of the two circular ends of a frustum are 20 cm and 12 cm and its height is 15 cm. Find its slant height and curved surface area. (\(\pi = 3.14\))

Doubtly Asked 29 Oct 2026 Practice test ssc 10th Save WhatsApp Report

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Answer: Slant height = 17 cm; CSA = 1708.16 cm\(^2\)

\(l = \sqrt{h^2 + (r_1 - r_2)^2} = \sqrt{15^2 + 8^2} = \sqrt{225 + 64} = \sqrt{289} = 17\) cm.

CSA \(= \pi (r_1 + r_2) l = 3.14 \times 32 \times 17 = 3.14 \times 544 = 1708.16\) cm\(^2\).

Doubtly AI · 29 Oct 2026 AI-verified · Nov 2026 Report

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