The three sides of a right triangle are 13cm, 12cm, 5cm respectively, what is its area in cm**2.
一个直角三角形的三条边分别是13cm，12cm，5cm，它的面积是多少cm**2．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<result>30</result>