(a) 306 m2
In the given figure, AECD is a rectangle.
Length AE = Length CD = 28 m
Now,
BE = AB - AE = 40 - 28 m
Also,
AD = CE = 9 m
Area of trapezium = 1/2 x sum of parallel sides x Distance between them
In the given figure, if DA is perpendicular to AE, then it can be solved, otherwise it cannot be solved.