A cone is 5cm high. Cut the cone into two equal parts through the bottom. The area of its longitudinal section is 10cm**2 Find the area of the bottom of the cone.
一个圆锥高5cm，通过底面把圆锥切成同样的两份，它的纵切面的面积是10cm**2求这个圆锥的底面积是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">10 * (2/5)</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>