Answer:
(13+x)cm
Step-by-step explanation:
Given data
Length of sides
1cm, 5cm, 7cm
Since the shape is four-sided and the fourth side is not given, let the fourth side be x
so
The perimeter of the polygon is
P= 1+5+7+x
P= 13+x
Hence the perimeter of the polygon is
P= (13+x)cm
