Use a compass to draw a circle with a diameter of 9 cm. What is the distance between the two feet of the compass in cm?
用圆规画一个直径是9厘米的圆，圆规两脚间的距离是多少厘米．
<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>