Answer:
52.5 inch square
Step-by-step explanation:
The maximum area of any polygon for a given perimeter is the area of a regular polygon. Here, the polygon is a quadrilateral. The regular quadrilateral is a square, and each side length is 1/4 of the perimeter.
(210 in)/4 = 52.5 in
The rectangle of maximum area is a square of side length 52.5 inches.
