Question

Suppose Xinwei want to put a fence around a rectangular field, where the width (w) is three times the length (l). Give an expression for the perimeter of the field in terms of its length (l).

Answer 1

P = 8 l

Explanation:

Let's consider a rectangular field with dimensions:

• width (w)

• length (l)

We know that the width (w) is three times the length (l), that is,

w = 3 l [1]

We can calculate the perimeter (P) of a rectangle using the following expression.

P = 2 l + 2 w [2]

If we replace [1] in [2], we get,

P = 2 l + 2 (3 l)

P = 2 l + 6 l

P = 8 l