right triangle has three sides whose lengths are 12 cm, 13 cm and 5 cm respectively, what is its area in square centimeters?
一个直角三角形，三条边长度分别为12厘米，13厘米，5厘米，它的面积是多少平方厘米．
<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>