Trapezoidal Graphs

    The purpose of trapezoidal graphs is to show slope change between data during different periods of time.

   The formula for finding the slope, is rise/run, which means the change in the y-axis divided by the change in the x-axis.  Steep slopes mean that it has changed fast and increased greatly. However, moderate slopes indicate the change is not much different than before. Slopes can either be positive or negative. Positive slopes mean the rate is increasing, and negative mean they are decreasing.

   Another thing we can find by using slope change is the area of each trapezoid. The formula to find area is to add the two sides of the trapezoid, dividing the sum by 2. Then, you multiply that answer by the change in the x-axis. By knowing the area, it is easy for us to visually see how each of the trapezoids differ in size.

   On the graph, the x-axis usually displays the different variables that are being compared. For example, on our mid-term test, our question that involved trapezoidal graphs, compared the bug populations of three different trees. Therefore, on the x-axis, you would display the three different trees. The y-axis displays a scale of numbers that are possible for each variable. Referring back to our test question, the y-axis would show the number of bugs in the trees. 

   Trapezoidal graphs are great to use in every day life to help us so