To find the length of the missing side of a figure when the perimeter is given, you'll need to know the lengths of the other sides of the figure. The perimeter is the total distance around the figure, which is found by adding the lengths of all the sides.
The formula for perimeter (P) is:
\( P = S_1 + S_2 + S_3 + \ldots + S_n \)
where \( S_1, S_2, S_3, \ldots, S_n \) are the lengths of the sides.
If you know the lengths of all sides except for the missing one, you can rearrange the formula to solve for the missing side (let's call it \( S_m \)):
\( S_m = P - (S_1 + S_2 + S_3 + \ldots + S_n) \)
If you provide the lengths of the other sides in your figure, I can help you calculate the length of the missing side.