Question

A large rectangle is made up of eleven
identical rectangles whose longer sides are 21
cm long. The perimeter of the large rectangle
in cm is
A) 150
B) 126
C) 108​

Answer 1

Answer:

218.4 cm

Step-by-step explanation:

The eleven rectangles can be placed as shown in the figure

Let the length of this rectangle be L and breadth be B

Longer side of one rectangle l = 21 cm

if the breadth of this rectangle is b then

l + 2b = B

or, 21 + 2b = B

Also,

3l = 5b

or, b = 3 × 21/5 = 63/5 cm

Thus B = 21 + 2 × 63/5

           = (105 + 126)/5

           = 231/5

And, L = 3l = 3 × 21 = 63 cm

Perimeter  = 2(L + B)

                 = 2(63 + 231/5)

                = 2(315 + 231)/5

               = 218.4 cm

Hope this is helpful.