Question

Rectangle divided into four rectangles. The perimeters of rectangle #1, #2, #3, #4 are 10 cm, 20 cm, 28 cm and 18 cm respectively. Find the perimeter of the big rectangle.

Answer 1

Perimeter of big rectangle = 38 units

Explanation:

Let the sides of rectangle (1) = a and c cm

Sides of rectangle (2) = b and c cm

Sides of rectangle (3) = b and d cm

Sides of rectangle (4) = a and d cm

Perimeter of (1) = 2(length + width)

2(a + c) = 10

a + c = 5 ---------(1)

Perimeter of (2) = 2(b + c)

2(b + c) = 20

b + c = 10 -------(2)

Perimeter of (3) =2(b + d)

2(b + d) = 28

b + d = 14 --------(3)

Perimeter of (4) = 2(a + d)

2(a + d) = 18

a + d = 9 -------(4)

Since perimeter of the big rectangle = 2(a + b + c + d)

By adding equations (1) + (2) + (3) + (4),

(a + c) + (b + c) + (b + d) + (a + d) = 5 + 10 + 14 + 9

2(a + b + c + d) = 38

Therefore, perimeter of the rectangle ABCD = 38 units