Cut the largest circle on a rectangular cardboard with a length of 8 cm and a width of 5 cm. What is the area of the circle in d㎡?
在一个长8cm、宽5cm的长方形纸板上剪一个最大的圆，圆的面积是多少d㎡
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) ** 2</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">3.14 * (25/4)</gadget>
<output>19.625</output>

<result>19.625</result>