Cut out a square with the largest area from a circular piece of paper with a radius of 10 cm. What is the area of the square?
利用半径为10厘米的圆形纸片剪成一个面积最大的正方形，此正方形的面积为多少．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">10 * 5 * 4</gadget>
<output>200</output>

<result>200</result>