The length of a rectangle is twice that of its breadth. The perimeter of a given rectangle is 90 cm. If length decreased by 5 cm and breadth increased by 5 cm, then the area of the rectangle increased by how much (In cm square)?
The length of a rectangle is twice that of its breadth. The perimeter of a given rectangle is 90 cm. If length decreased by 5 cm and breadth increased by 5 cm, then the area of the rectangle increased by how much (In cm square)? Correct Answer 50
Let ‘l’ be the length of a given rectangle and ‘b’ be its breadth.
Here, l = 2b (given)
Perimeter of rectangle = 2(l + b)
⇒ 2 (2b + b) = 90
⇒ 3b = 45
⇒ b = 15 cm
⇒ length l = 2b = 30 cm
Now, when length decreased by 5 cm and breadth increased by 5 cm,
Then, increase in the area of rectangle = (new area) – (old area)
= (30 – 5) * (15 + 5) – (30 * 15)
= 500 – 450
= 50 cm square
Hence, increase in the area of rectangle is 50 cm square
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Feb 20, 2025