A trough has an isosceles trapezoidal cross section as shown in the diagram. Water is draining from the trough at 0.2m^3/s
At what rate is the surface rea of the water decreasing?
Dimensions are: base width=0.4m,
top width= 0.8m
The Attempt at a Solution
Ok I really really don'tknow where to start, if maybe someone can give me a clue