To determine the perimeter of the trapezoid, we just have to determine the distance between the pair of points which can be calculated through the equation,
d = √(x₂ - x₁)² + (y₂ - y₁)²
Substituting,
(1,4) and (-2,0) d = √(1 - -2)² + (4 - 0)² = 5
(-2,0) and (7,0) d= √(-2 - 7)² + (0 - 0)² = 9
(7,0) and (3,4) d = √(7 - 3)² + (0 - 4)² = 5.66
(3,4) and (1,4) d = √(3 - 1)² + (0 - 0)² = 2
The perimeter is the sum of the distances. Thus, the answer is 21.66.