Cut off an iron plate with a length of 3 meters and a width of 1 meter to the largest semicircular iron plate. What is the area of the semicircular iron plate in square meters?
把一块长3米，宽1米的铁板截下一个最大半圆形铁板，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>