<em>Answer:</em>
<em>8m</em>
<em>Step-by-step explanation:</em>
<em>We can convert the trapezium into a rectangle to make finding the area easier.</em>
<em>Say that the top side is 9m, and that the bottom side is 12m.</em>
<em>12 - 9 = 3</em>
<em>3/2* = 1.5</em>
<em>*Note that we are dividing by two to get the "overhang" of the bottom side.</em>
<em>Now that we have our overhang, we can find the length of the "t-rect"**.</em>
<em>**"T-rect" refers to a rectangle that has been formed by changing a trapezium into a rectangle.</em>
<em>12 - 1.5 = 10.5</em>
<em>9 + 1.5 = 10.5</em>
<em>The length of the t-rect is 10.5.</em>
<em>84/10.5 = 8</em>
<em>The height of the t-rect is 8m.</em>
<em>Since the height of the original trapezium is equal to the height of the t-rect***, </em>
<em>***Since we have only adjusted the length</em>
<em>this also means that 8m would also be the height of the original trapezium.</em>
<em>Now, there is a second way of doing this.</em>
<em>Find the median of 12 and 9.</em>
<em>9, 10, 11, 12</em>
<em>10, 11</em>
<em>The median is 10.5.</em>
<em>84/10.5 = 8</em>
<em>You get the same answer. These methods could be used as a solve-then-check method to another problem like these.</em>
<em>Hope this helps. Have a nice day.</em>
