Fold a circular piece of paper in half so that the upper and lower parts overlap completely. Measure the length of the crease to be 3 cm. What is the area of the circular piece of paper in square centimeters?
把一个圆形纸片对折，使上下两部分完全重合，量出折痕的长是3厘米，这个圆形纸片的面积是多少平方厘米．
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) ** 2</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">3.14 * (9/4)</gadget>
<output>7.065</output>

<result>7.065</result>