Answer: 25.6 units
Explanation:
In the given picture , it can be seen that the triangle is passing through three points (-5,4) , (1,4) and (3, -4).
Using distance formula , we find the side -lengths of the triangle.
The distance between two points (a,b) and (c,d) is given by :_

The distance between two points (-5,4) and (1,4):

The distance between two points (1,4) and (3, -4).:

The distance between two points (-5,4) and (3, -4).:

Now, the perimeter of triangle =

( to the nearest tenth of a unit)
Hence, the perimeter of the triangle shown on the coordinate plane. = 25.6 units