The circumference of a circle is 12.56 cm. With one of its diameters as the base, draw a largest triangle inside the circle. What is the area of this triangle in square centimeters?
一个圆的周长是12.56厘米，以它的一条直径为底边，在圆内画一个最大的三角形，这个三角形面积是多少平方厘米．
<gadget id="calculator">12.56 / 3.14</gadget>
<output>4</output>

<gadget id="calculator">12.56 / 3.14 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">4 * 1</gadget>
<output>4</output>

<result>4</result>