There is a right triangle, the two sides of which are two different prime numbers, and their sum is 12cm. What is the area of this right triangle in cm**2.
有一个直角三角形，两条直角边是两个不同的质数，它们的和是12cm．这个直角三角形的面积是多少cm**2．
<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">5 * (7/2)</gadget>
<output>35/2 = around 17.5</output>

<result>35/2 = around 17.5</result>