Draw the largest circle on a square with a side length of 8 cm. What is the distance between the two feet of the compass in cm?
在一个边长8厘米的正方形画一个最大的圆，圆规两脚间的距离应取多少厘米．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<result>4</result>