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Mathematics

Each side of a rectangle is doubled. Find the ratio between :

(i) perimeters of the original rectangle and the resulting rectangle

(ii) areas of the original rectangle and the resulting rectangle

Area Trapezium Polygon

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Answer

(i) Given:

Each side of a rectangle is doubled.

Let the length and breadth of the rectangle be l and b.

Thus, the new length and breadth of the rectangle are 2l and 2b.

As we know, the perimeter of a rectangle = 2 (length + breadth)

The perimeter of the original rectangle = 2 (l + b)

The perimeter of the new rectangle = 2 (2l + 2b)

= 4 (l + b)

Thus, the ratio of the perimeters of the original rectangle and the resulting rectangle = 2(l+b)4(l+b)\dfrac{2 (l + b)}{4 (l + b)}

= 2(l+b)4(l+b)\dfrac{2 \cancel{(l + b)}}{4 \cancel{(l + b)}}

= 24\dfrac{2}{4}

= 12\dfrac{1}{2}

Hence, the ratio of the perimeters of the original rectangle and the resulting rectangle is 12\dfrac{1}{2}.

(ii) As we know, the area of a rectangle = length x breadth

The area of the original rectangle = l x b

= lb

The area of the new rectangle = 2l x 2b

= 4 lb

Thus, the ratio of the areas of the original rectangle and the resulting rectangle = lb4lb\dfrac{lb}{4lb}

= lb4lb\dfrac{\cancel{lb}}{4 \cancel{lb}}

= 14\dfrac{1}{4}

Hence, the ratio of areas of the original rectangle and the resulting rectangle is 14\dfrac{1}{4}.

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