What is the diameter of a tree around which is 3m 9dm 7cm long rope wrapped? How big is its cross-sectional area?

Result

D =  1.264 m
S =  1.255 m2

Solution:

$o = 3+9/10+7/100 = \dfrac{ 397 }{ 100 } = 3.97 \ m \ \\ o = \pi \cdot \ D \ \\ D = o/\pi = 3.97/3.1416 \doteq 1.2637 = 1.264 \ \text { m }$
$r = D/2 = 1.2637/2 = \dfrac{ 79 }{ 125 } = 0.632 \ m \ \\ S = \pi \cdot \ r^2 = 3.1416 \cdot \ 0.632^2 \doteq 1.2548 = 1.255 \ m^2$

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