Detailed description
- Area under a constant function. Straight-line graph, line parallel to the x axis intersecting the positive y axis, region shaded between points marked on the x axis as a and b and graph.
- Area under a linear function, correctly estimated by midpoint or trapezoidal estimate. Straight line graph, diagonal line intersecting negative x axis and positive y axis, with 4 rectangles with midpoints determining each of their heights marked as a and b. First rectangle starts from x = a and fourth rectangle finishes at x = b.
