Question

breadth is 4cm perimeter is 20 and area is 24 sq.cm find the length

explain these question step by step​

Answer 1

Answer:

We know that perimeter of a rectangle is 2(l + b)

Given, Perimeter = 2(l + b) = 20cm

=> l + b = 20/2

=> l + b = 10cm ..(i)

We know that area of a rectangle = length × breadth

Given, Area = L × B = 24

=> lb = 24...(ii)

Now,

squaring both sides in (i) equation

(l + b)² = (10)²

=> l² + b² + 2lb = 100

putting value of lb we get

=> l² + b² + 2(24) = 100

=> l² + b² + 48 = 100

=> l² + b² = 100 - 48

=> l² + b² = 52

Now subtracting 2lb from both sides,

l² + b² - 2lb = 52 - 2lb

Putting value of lb in RHS

l² + b² - 2lb = 52 - 2(24)

=> l² + b² - 2lb = 4

We can write,

(l - b)² = (2)²

=> l - b = 2 ...(iii)

Adding (i) and (iii)

l + b + l - b = 10 + 2

=> 2l = 12

=> l = 12/2 = 6

{Length \:= \:6cm}

Putting l in (i)

l + b = 10

=> 6 + b = 10

=> b = 10 - 6 = 4cm

\boxed{Breadth\: =\: 4cm}

Hope it helps dear friend ☺️