Question

прямоугольник имеет длину 42 дм. и ширину 1,5м. . длину этого прямоугольника увеличили на 80 см. ,а ширину уменьшили на 20% . на сколько квадратных метров уменьшилась или увеличилась площадь этого прямоугольника?

Answer 1

Calculation of the Rectangle's Area

To calculate the change in the area of the rectangle, we need to find the initial area and the final area after the changes in length and width.

The initial length of the rectangle is 42 dm, which is equivalent to 4.2 m. The initial width is 1.5 m.

The initial area of the rectangle is calculated by multiplying the length and width:

Initial Area = Initial Length x Initial Width

Initial Area = 4.2 m x 1.5 m

To find the final length and width, we need to consider the changes that occurred. The length was increased by 80 cm, which is equivalent to 0.8 m. The width was decreased by 20%.

To calculate the final length, we add the change to the initial length:

Final Length = Initial Length + Length Change

Final Length = 4.2 m + 0.8 m

To calculate the final width, we multiply the initial width by (1 - Width Change Percentage):

Final Width = Initial Width x (1 - Width Change Percentage)

Final Width = 1.5 m x (1 - 0.2)

Now that we have the final length and width, we can calculate the final area of the rectangle:

Final Area = Final Length x Final Width

Final Area = (4.2 m + 0.8 m) x (1.5 m x (1 - 0.2))

Let's calculate the final area:

Final Area = 5 m x 1.2 m

Final Area = 6 m²

Answer:

The area of the rectangle increased by 6 square meters.