Question

1. The length of a rectangle exceeds it's width by 4 m . if perimeter is 40 m , find its dimensions

Answer 1

ANSWER:-
Let width of the rectangle be x metres,
Then, length = (x+4)m
Perimeter=40m.
Perimeter of a rectangle = 2(l+b)......(i)
Putting value of l and b in equation (i) we get,
⇒40=2(x+4+x)
⇒40=2(2x+4)
⇒40/2=2x+4
⇒20-4=2x
⇒16=2x
⇒x=8
Therfore, 
breadth = x = 8m
and length = x+4=8+4=12m.

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Answer 2

let the length of rectangle be x
let the breadth of rectangle be y

case 1:
x - y = 4
x = 4 + y ________(eqn 1)

case 2:
perimeter of rectangle = 2( l + b )
40 = 2 (x + y)
40/2 = x + y
20 = x + y ________(eqn2)

putting (eqn 1) in (eqn2)
20 = x + y
20 = (4 + y) + y
20 - 4 = 2y
16/2 =y
8 = y

put y = 8 in (eqn 1)
x = 4 + y
x = 4 + 8
x = 12
therefore length = 12m
therefore breadth = 8m