Take note that a trapezoid is a quadrilateral and at least two of its sides are parallel.
Its formula of area is:
where b1 is base 1, b2 is base 2 and h is the height.
Base1 and base2 are the parallel sides. And the height is the line perpendicular to the two bases.
The possible trapezoids that we can have when the area is 56 cm^2 are:
(1) b1 = 6 cm, b2 = 10 cm, h = 7 cm (See Figure 1)
(2) b1 = 9 cm, b2 = 5 cm, h = 8 cm (See Figure 2.)