Assuming I’m reading your question correctly, that the area is 42 square feet…
The length of each side is then sqrt(42) feet or about 6.480741 feet.
Since a square has four sides, you’d have 4*6.480741 for the perimeter, or about 25.922964 feet.
Rounding this to the hundredths place, you’d have 25.92 feet.
