The lengths of the three sides of a right triangle are 5 cm, 13 cm, and 12 cm respectively. What is its area?
一直角三角形三条边的长分别是5厘米、13厘米、12厘米，它的面积是多少．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">12 * (5/2)</gadget>
<output>30</output>

<result>30</result>