40 trees are planted around a circular flower bed, and the distance between every two trees is 1.57 meters. What is the radius of the flower bed in meters?
一个圆形花坛四周种了40棵树，每两棵树之间的距离是1.57米，这个花坛的半径多少米？
<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

<gadget id="calculator">40 / 6.28</gadget>
<output>6.369427</output>

<gadget id="calculator">1.57 * 6.369427</gadget>
<output>10</output>

<result>10</result>