The length of the rectangle is 7 cm, and the width is 3 cm. How will its perimeter change if the length

| September 4, 2021 | education

The length of the rectangle is 7 cm, and the width is 3 cm. How will its perimeter change if the length and width are increased by 5 cm? If the length is reduced by 4 cm and the width is increased by 3 cm?

Let’s calculate the perimeter of this rectangle:

P = 2 * (7 + 3) = 2 * 10 = 20 cm.

1) Let’s increase the length and width of the first rectangle by 5 cm and calculate its perimeter.

a = 7 + 5 = 12 cm;

b = 3 + 5 = 8 cm.

P = 2 * (12 + 8) = 2 * 20 = 40 cm.

Let’s compare the perimeters of the rectangles:

40 – 20 = 20 cm, the perimeter has increased by 20 cm.

2) Reduce the length by 4 cm, increase the width by 3 cm and calculate the perimeter.

a = 7 – 4 = 3 cm;

b = 3 + 3 = 6 cm.

P = 2 * (3 + 6) = 2 * 9 = 18 cm.

20 – 18 = 2 cm, the perimeter has decreased by 2 cm.



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