The length of a side of an isosceles right triangle is 4.2 cm, what is the area of the triangle?
一个等腰直角三角形的直角边长4.2cm，这个三角形的面积是多少．
<gadget id="calculator">4.2 / 2</gadget>
<output>2.1</output>

<gadget id="calculator">4.2 * 2.1</gadget>
<output>8.82</output>

<result>8.82</result>