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Question
The external radius and the length of a hollow wooden log are 16 cm and 13 cm respectively. If its thickness is 4 cm then find its T.S.A
Solution
External radius of the wooden log (R) = 16 cm
Thickness = 4 cm
Internal radius (r) = 16 – 4 = 12 cm
Length of the wooden log (h) = 13 cm
T.S.A of the hollow cylinder = 2π (R + r) (R – r + h) sq.cm
= `2 xx 22/7 xx (16 + 12)(16 - 12 + 13) "sq.cm"`
= `2 xx 22/7 xx 28 xx 17 "sq.cm"`
= 2 × 22 × 4 × 17 sq.cm.
= 2992 sq.cm.
T.S.A of the hollow wooden = 2992 sq.cm
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