The lengths of the three sides of a right triangle are 3dm, 4dm and 5dm respectively. What is the area of the right triangle?
一个直角三角形的三条边长分别是3dm，4dm和5dm，这个直角三角形的面积是多少．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<result>6</result>