Question

which measurement below has a perimeter of 18 km? length = 10 km; width = 8 km length = 2 km; width = 7 km length = 7 km; width = 7 km length = 2 km; width = 9 km

Explanation:

Step1: Recall perimeter formula for rectangle

The formula for the perimeter \( P \) of a rectangle is \( P = 2\times(\text{length} + \text{width}) \).

Step2: Calculate perimeter for first option

For length = 10 km and width = 8 km:
\( P = 2\times(10 + 8) = 2\times18 = 36 \) km.

Step3: Calculate perimeter for second option

For length = 2 km and width = 7 km:
\( P = 2\times(2 + 7) = 2\times9 = 18 \) km.

Step4: Calculate perimeter for third option

For length = 7 km and width = 7 km (a square, which is a special rectangle):
\( P = 2\times(7 + 7) = 2\times14 = 28 \) km.

Step5: Calculate perimeter for fourth option

For length = 2 km and width = 9 km:
\( P = 2\times(2 + 9) = 2\times11 = 22 \) km.

Answer:

Length = 2 km; Width = 7 km