Question

5196

A large rectangle is made by joining three identical small rectangles as shown.
The perimeter of one small rectangle is 21 cm.
The width of one small rectangle is x cm.
x cm
Work out the perimeter of the large rectangle.
The final line of your answer should be of the form,
Perimeter of large rectangle is ... cm

Answer 1

35 cm

Explanation:

As shown in the image attached, the A large rectangle is made by joining three identical small rectangles,

The width of one small rectangle is x cm and the length of one small rectangle is 2x cm. Therefore the perimeter of the small rectangle is given as:

2(length + width) = Perimeter

2(2x + x) = 21

2(3x) = 21

6x = 21

x = 21/6 = 3.5 cm

x = 3.5 cm

From the image attached, the width of the large rectangle is 2x (x + x) and the length is 3x (2x + x). Therefore, the perimeter of the large rectangle is:

2(length + width) = Perimeter

2(3x + 2x) = Perimeter

Perimeter = 2(5x)

Perimeter = 10x

Perimeter = 10(3.5)

Perimeter = 35 cm