There is an isosceles triangle with a vertex and a base angle in a ratio of 2:1, and the longest side of this triangle is 25 cm. What is the area of this triangle in square centimeters?
有一个等腰三角形，顶角和一个底角的度数比是2：1，这个三角形最长的边长是25厘米．这个三角形的面积是多少平方厘米？
<gadget id="calculator">25 / 2</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">25 * (25/2)</gadget>
<output>625/2 = around 312.5</output>

<gadget id="calculator">(625/2) / 2</gadget>
<output>625/4 = around 156.25</output>

<result>625/4 = around 156.25</result>