Question

the perimeter of the figure below is 261 m. find the length of the missing side.

Explanation:

Step1: Sum up the known side - lengths

First, count the number of each known - length side. There are 8 sides of length 19 m, 2 sides of length 35.8 m, and 1 side of length 19.2 m. The sum of the known side - lengths is $8\times19 + 2\times35.8+19.2$.
$8\times19=152$, $2\times35.8 = 71.6$, so $8\times19 + 2\times35.8+19.2=152 + 71.6+19.2=242.8$ m.

Step2: Find the length of the missing side

The perimeter of the figure is 261 m. Let the length of the missing side be $x$. We know that the perimeter is the sum of all side - lengths. So $242.8+x = 261$. Solving for $x$, we get $x=261 - 242.8=18.2$ m.

Answer:

18.2 m