What is the area of an equilateral triangle whose perimeter is 15 cm and height is 6 cm?
一个等边三角形的周长是15厘米，高是6厘米，它的面积是多少平方厘米．
<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>