Question

the perimeter of a rectangle is 70 cm if its breadth is 5 cm less than the length find its area

Answer 1

Answer:

300cm sq

Step-by-step explanation:

2(l+b)=70

b=l-5

2(l=l-5)=70

2(2l-5)=70

4l-10=70

4l=70+10=80

l=20

b=l-5=20-5=15

l*b=20*15=300 cm sq

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Answer 2

It is given that the breadth of the rectangle is 5 cm less than the length of the same rectangle.

Let the length of the rectangle be a cm, and breadth of the rectangle be ( a - 5 ) cm i.e. 5 cm less than a cm, which is the length of the rectangle.


Now,
Length of the rectangle is a cm
Breadth of the rectangle is ( a - 5 ) cm



According to the question :

Perimeter of the rectangle = 70 cm


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From the properties of rectangle, we know
Perimeter of rectangle = 2( length + breadth )
=============

Thus,

= > 2{ a cm + ( a - 5 ) cm } = 70 cm

= > 2( a cm + a cm - 5 cm ) = 2 x 35 cm


Cancelling 2 from both sides,

= > 2a cm - 5 cm = 35 cm

= > 2a cm = 40 cm

= > a cm = 20 cm


Hence,
Length of the rectangle = a cm = 20 cm

Breadth of the rectangle = ( a - 5 ) cm = ( 20 - 5 ) cm = 15 cm


=============
From the properties of rectangle, we know
Area of rectangle = length x breadth
=============


Therefore,
Area of this rectangle = 20 cm x 15 cm

Area of this rectangle = 300 cm²



Hence,
Area of the rectangle is 300 cm².
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