Draw a largest circle inside the square. The diameter of the circle is 5 cm. What is the perimeter of the square in cm?
在正方形里面画一个最大的圆，圆的直径为5厘米，正方形的周长是多少厘米．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>