Perimeter of a Parallelogram

Example 7.4.1: 

A parallelogram has sides measuring 20 cm by 25 cm. What is the Perimeter?

Solution

a = 20 cm

b = 25 cm

Perimeter = 2 (a  +  b)

Perimeter  = 2(20  +  25)

= 2(45)

= 2 × 45

= 90 cm

Example 7.4.2:

A parallelogram has sides measuring 250 mm by 200 mm. What would be the length of the side of a square having the same perimeter?

 

Solution:

Length of the parallelogram   =   250 mm

Breadth/Width of the parallelogram   = 200 mm

Perimeter p = 2 (a   + b)

P =   2 (250 + 200)

P =   2(450)

P = 900 mm

Therefore the perimeter of the square =  900 mm (i.e. the same as the perimeter of the parallelogram).

But the perimeter of a square is

P =   4 × length 

i.e.  900 =  4 × length

Divide both sides by 4

\( \frac{900}{4} = \frac{4 \: \times \: length}{4} \)

Length  = \( \frac{900}{4}\)

Length = 225 mm