Mathematics for IGCSE & O level - Mensuration (Section 8 - No. 7)
To calculate the perimeter of a 2-D shape, what do you need to know?
The area of the shape.
The volume of the shape.
The lengths of all the sides of the shape.
The height of the shape.
Explication
Perimeter is the total length of all sides, so you need the length of all sides.