LENGTH OF MISSING SIDE OF 2D SHAPE FROM PERIMETER

Problem 1 :

Solution :

Perimeter = 26 cm

Length = 8 cm

Perimeter of rectangle = 2l + 2w

26 = 2(8) + 2w

26 = 16 + 2w

2w = 26 - 16

2w = 10

w = 5 cm

The length of the missing side is 5 cm.

Problem 2 :

Solution :

Given, perimeter = 80 cm

Width = 14 cm

Perimeter of rectangle = 2l + 2w

80 = 2l + 2(14)

80 = 2l + 28

2l = 80 - 28

2l = 52

l = 52/2

l = 26 cm

The length of the missing side is 26 cm.

Problem 3 :

Solution :

Perimeter = 20 cm

Perimeter of square P = 4a

20 = 4a

a = 20/4

a = 5

The length of the missing side is 5 cm.

Problem 4 :

Solution :

Given, perimeter = 25 cm

Side a = 9 cm, b = 9 cm

Perimeter of triangle P = a + b + c

25 = 9 + 9 + c

25 = 18 + c

c = 25 - 18

c = 7 cm

The length of the missing side is 7 cm.

Problem 5:

Solution :

Perimeter = 36 cm

Perimeter of equilateral triangle P = 3 × a

36 = 3 × a

a = 36/3

a = 12 cm

The length of the missing side is 12 cm.

Problem 6 :

Solution :

Perimeter = 79 cm    

Side b = 35 cm

Perimeter of triangle P = 2a + b

79 = 2a + 35

2a = 79 - 35

2a = 44

a = 44/2

a = 22 cm

The length of the missing side is 22 cm.

Problem 7 :

Solution :

Given, perimeter = 45 cm    

Width = 9 cm

Perimeter of rectangle P = 2(l + w)

45 = 2(l + 9)

45 = 2l + 18

2l = 45 - 18

2l = 27

l = 13.5 cm

The length of the missing side is 13.5 cm.

Problem 8:

Solution :

Given, perimeter = 2 m        

Perimeter of pentagon = 5 × a

2 = 5a

a = 2/5

a = 0.4 m

The length of the missing side is 0.4 m.

Problem 9 :

Solution :

Given, Perimeter = 163 cm

x + x + 32 + 32 + 25 = 163

2x + 89 = 163

2x = 163 - 89

2x = 74

x = 74/2

x = 37 cm

The length of the missing side is 37 cm.