Draw a circle inside a rectangle with a length of 8 cm and a width of 4 cm. What is the maximum radius of this circle in cm?
在一个长8厘米，宽4厘米的长方形内画一个圆，这个圆的半径最大可以是多少厘米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<result>2</result>