Answer
(4 ft) $\times$ (4 ft).
Work Step by Step
Let the sheet metal have side x.
Taking away two 1-foot lengths from the width,
and two 1-foot lengths from the height of the sheet, what remains is a base square
with area $(x-2)^{2} $.
The height of the box is 1,
so we are given (with volume =4)
$(x-2)^{2}=4$
$(x-2)^{2}=2^{2}$
$x-2=\pm 2$
$x=2\pm 2$
The x=0 solution makes no sense,
so the only solution is x=4.
The original sheet is (4 ft) $\times$ (4 ft).
