Answer:
18 unit
Step-by-step explanation:
By plotting the given points on the coordinate plane ( shown below )
We get a rectangle.
Suppose ABCD is a rectangle such that,
A≡(-1,1), B≡(3,1), D≡(3,-4) and C≡(-1,-4),
By the distance formula,
\(AB=\sqrt{(3-(-1))^2+(1-1)^2}=\sqrt{(3+1)^2+0}=\sqrt{4^2}=4\text{ unit}\)
\(BC=\sqrt{(3-3)^2+(-4-1)^2}=\sqrt{0+5^2}=\sqrt{5^2}=5\text{ unit}\)
∵ Perimeter of a rectangle = 2 ( sum of any two adjacent sides )
Thus, the perimeter of the rectangle ABCD = 2(AB + BC)
= 2(4+5)
= 2(9)
= 18 unit
