If the base of a triangle is 7 decimeters and twice its height, what is its area in square decimeters?
一个三角形的底是7分米，是高的2倍，它的面积是多少平方分米．
<gadget id="calculator">22.5 / 2</gadget>
<output>11.25</output>

<result>11.25</result>