A right triangle with a height of 2m and a base of 4m. Calculate the actual area of the triangle.
一个高是2m，底是4m的直角三角形．计算三角形的实际面积．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>