By definition, the area of a square is given by:
\(A = L ^ 2
\)
Where,
L: length of the sides of the square.
Substituting values we have:
\(L ^ 2 = 81
\)
From here, we clear the value of L.
We have then:
\(L = \sqrt{81}
L = 9 in
\)
Answer:
the length of the cardboard is:
\(L = 9 in\)
