Answer:
20 units
Explanation:
The polygon has 4 vertices as indicated by the 4 coordinate points given.
(3, 1) and (8, 1) is a horizontal side of length 8 - 3 = 5
Similarly
(3, 6) and (8, 6) is the opposite horizontal side of length 8 - 3 = 5
Points (3, 1) and (3, 6) is a vertical side of length 6 - 1 = 5
(8, 1) and (8, 6) is the opposite side of length 6 - 1 = 5
The polygon is therefore a square of side 5 units.
Perimeter = 4 × 5 = 20 units