Answer:
The length of a side of the square is 4.53 cm
Explanation:
Volume (V) = mass/density
mass = 3.4 mg = 3.4/1000 = 0.0034 g
density = 19.3 g/cm^3
V = 0.0034/19.3 = 1.76×10^-4 cm^3
Volume = area × thickness
Area = volume/thickness = 1.76×10^-4/8.6×10^-6 = 20.48 cm^2
Length of one side of the square = sqrt(area of square) = sqrt(20.48 cm^2) = 4.53 cm