Build a cylindrical cistern with a depth of 2.2 meters and a bottom diameter of 4 meters. How many square meters does this cistern occupy?
修一个深2.2米，底面直径为4米的圆柱形蓄水池，这个蓄水池，这个蓄水池占地多少平方米
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 2 * 2</gadget>
<output>12.56</output>

<result>12.56</result>