If the two sides of a right triangle are 5 cm and 4 cm respectively, what is its area in square centimeters?
一个直角三角形的两条直角边分别为5厘米和4厘米，它的面积是多少平方厘米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<result>10</result>