How many meters would it take to surround a semicircular flower bed with a radius of 3 meters.
要给一个半径3米的半圆形花坛围上栏杆，要围多少米．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 3 * 1</gadget>
<output>9.42</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">9.42 + 6</gadget>
<output>15.42</output>

<result>15.42</result>