Use a rope with a length of 109.9 meters to go around the trunk exactly 10 times, and find the diameter of the cross section.
用一根长109.9米的绳子正好围绕树干10周，求横截面的直径．
<gadget id="calculator">109.9 / 10 / 3.14</gadget>
<output>3.5</output>

<result>3.5</result>