Answer:
19.11 square units
Step-by-step explanation:
The fish tank is composed by eight rectangles with base = 0.9 units and height = 2 units; and by a regular octagon at the bottom, which sides are 0.9 units long.
Area of each rectangle = 0.9*2 = 1.9 square units
Area of the regular octagon = 2*(1 + √2)*0.9² = 3.91 square units
Therefore:
Surface area of the fish tank = 8*1.9 + 3.91 = 19.11 square units
