3. There are no charts
4. If the radius of the upper semicircle is r, then the area of the whole window is πR? /2+R？ = 2m2, we can get r = 0.8820...m ≈ 0.88m
5. No charts
Supplementary questions. It can be concluded from the number of fish that it needs at least 400m? The volume of. Let the depth of the pond be r, then if the pond is cylindrical, π*R? *2=400, the solution is r ≈ 7.98m; If the pond is conical, π*R? *2/3=400, and R≈ 190.96m is obtained.