Question

If the length of rectangle is incresed 40% and its bredth in dreased by 40%. What Will be the percentage change in its perimeter
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Answer 1

Answer:

Let P equal the perimeter, L equal the length, and B equal the breadth.

The calculation for perimeter (for a rectangle/square) is : P = 2L + 2B

The easiest way to move from here is to plug in example numbers. For this example, we’ll use 10 as each the length and breadth [this is due to the assumption that the figure in question is a square].

This yields: P = 2(10) + 2(10)

P = 20+20

P = 40

This shows that our original rectangle has a perimeter of 40 units.

If each the breadth isdecreased by 40%, then 60% will remain (100% - 40% = 60%), so 0.6B and 1.4L will be the new dimensions

Making this a new equation:

P = 2(1.4L) + 2(0.6B)

Plugging in 10 and solving for P:

P = 2(1.4(10)) + 2(o.6(10))

P = 28 + 12

P = 40

The new perimeter after the decrease is now 40 units.

As you can see, the perimeters are equal both before and after the change, so no change in the perimeter’s value occurred.

You can test this by plugging in any value for the length and breadth (as long as the length = the breadth)

I hope this answered your question! Any questions, just let me know.