If the perimeter of an equilateral triangle is 30 cm and the height is 8.5 cm, what is the area in square centimeters?
一个等边三角形的周长是30厘米，高是8.5厘米，面积是多少平方厘米．
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">8.5 / 2</gadget>
<output>4.25</output>

<gadget id="calculator">10 * 4.25</gadget>
<output>42.5</output>

<result>42.5</result>