Cut the largest semicircle out of a rectangular piece of paper with a length of 15 cm and a width of 6 cm. What is the area of this semicircle?
在长15厘米、宽6厘米的长方形纸片上剪下一个最大的半圆，这个半圆的面积是多大？
<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<gadget id="calculator">3.14 * 18</gadget>
<output>56.52</output>

<result>56.52</result>