The three sides of a right triangle are 30 cm, 40 cm and 50 cm respectively, what is its area in square centimeters?
一个直角三角形的三条边分别是30厘米、40厘米和50厘米，它的面积是多少平方厘米．
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">40 * 15</gadget>
<output>600</output>

<result>600</result>