Use an iron wire with a length of 12.4 decimeters to form an isosceles trapezoid. It is known that the two sides of the trapezoid have a total length of 6.4 decimeters and an area of 9 square decimeters. What is the height of this trapezoid?
用一根长12.4分米的铁丝围成一个等腰梯形，已知这个梯形的两腰共长6.4分米，面积是9平方分米，这个梯形的高是多少分米？
<gadget id="calculator">12.4 - 6.4</gadget>
<output>6</output>

<gadget id="calculator">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">9 * (1/3)</gadget>
<output>3</output>

<result>3</result>