Answer:
square; perimeter 20 units; area 25 square units.
Explanation:
As the attachment shows, each side of the polygon is the hypotenuse of a 3-4-5 right triangle, so has length 5 units. The perimeter is the sum of those lengths, 4×5 = 20; the area is the product of the lengths of adjacent sides, 5×5 = 25.
The figure is a square of side length 5 units.
The perimeter is 20 units; the area is 25 square units.