There is a steel plate in a right triangle. The lengths of the three sides are 15cm, 20cm, and 30cm respectively. What is the area of the steel plate in square centimeters?
有一块直角三角形的钢板，量得三条边的长度分别是15cm、20cm、30cm，这块钢板的面积是多少平方厘米．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<result>150</result>