Answer:
8√5 units.
Step-by-step explanation:
See the diagram in the coordinate plane attached.
A rhombus has four equal sides and to find the perimeter of the rhombus we have to measure any of the sides of the figure of the rhombus.
The coordinates of the topmost point are (-1,-1) and that of the rightmost point are (3,-3).
Therefore, side length of the rhombus will be  
 units.
 units.
So, the perimeter of the rhombus will be (4 × 2√5) units  = 8√5 units. (Answer)
The distance between two points  and
 and  on a coordinate plane is given by
 on a coordinate plane is given by  
