Find the area of the rectangle, the hint gives us when you put the rectangle on its side can be multiplied it by 1/2 it will be the same as the length that we need for the area formula.

Answer:
11700 mm²
Step-by-step explanation:
Vertical height between the centres of top and bottom circles
sqrt[(2×28)² - 28²]
= 28sqrt(3)
Width of the rectangle
= 4×28
= 112
Length of the rectangle
= 28sqrt(3) + 2(28)
= 56 + 28sqrt(3)
Area = 112 × (56 + 28sqrt(3))
= 11703.71133 mm²