We will have the following:
Inferring from the information presented in the diagram we can conclude that the measurements will be:
Base: 3ft * 12ft = 36f t^2
Side1: 3ft * 2ft = 6 ft^2
Side 2: 12ft * 2ft = 24 ft^2
So, the values that would represent the dimension will be:
Length: 12 ft.
Width: 3 ft.
Height: 2 ft.