The perimeter of an isosceles triangle is 16cm, the waist length is 5cm, and the height above the base is 4cm. What is the area of this isosceles triangle in cm**2.
等腰三角形的周长是16cm，腰长是5cm，底边上的高是4cm，这个等腰三角形的面积是多少cm**2．
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">16 - 10</gadget>
<output>6</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<result>12</result>