Question

The length (L) of a rectangle is twice its breadth (B).If its perimeter is 30cm ,find the length and breadth of the rectangle
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Answer 1

Step-by-step explanation:

40 cm

Let breadth=x

⇒ Length=2x

⇒ Area of rectangle=2x×x

=2x2

After the given changes;

length=2x−5

Breadth=x+5

Area=2x2+75

⇒(2x−5)(x+5)=2x2+75

2x2−5x+10x−25=2x2+75

5x=75+25=100

⇒x=20

⇒ Breadth=20cm

Length=40cm.

Answer 2

Given :-

Length is twice its breadth

Perimeter = 30 cm

To Find :-

Length and Breadth

Solution :-

Let the breadth be x and length be 2x

• Perimeter = 2(l + b)
• 30 = 2(2x + x)
• 30/2 = 2x + x
• 15 = 3x
• 15/3 = x
• 5 = x

Hence

• Length = 2x
• 2(5) = 10 cm
• Breadth = x
• 1(5) = 5 cm