Cut a triangle as large as possible from a semicircle with a radius of 10 cm, what is the area in square centimetres?
从半径为10厘米的半圆中，剪一个尽可能大的三角形，剪成后的面积是多少平方厘米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">10 * 2 * 5</gadget>
<output>100</output>

<result>100</result>