Cut the largest semicircular iron plate from a rectangular iron plate with a length of 3 meters and a width of 1 meter. What is the area of the semicircular iron plate in square meters?
在一块长3米，宽1米的长方形铁板上截下一块最大的半圆形铁板，半圆形铁板的面积是多少平方米？
<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3.14 * (1/2)</gadget>
<output>1.57</output>

<result>1.57</result>