It is known that the circumference of a rectangle is 40cm. If its length and width are increased by 5cm, its area will be increased______ cm2．

It is known that the circumference of a rectangle is 40cm. If its length and width are increased by 5cm, its area will be increased______ cm2．

As shown in the figure: let the length of the original rectangle be a centimeter and the width be B centimeter. According to the meaning of the title, a sum of length and width: a + B = 40 △ 2 = 20 (CM), the area is ab square centimeter; the length and width are increased by 5 meters respectively, and the area is: (a + 5) × (B + 5) = AB + 5 (& nbsp; A + b) + 25 (square centimeter), the area will increase: ab + 5 (a + b) + 25 AB = 5 × 20 + 25 = 125 (square centimeter)

When the length and width of a rectangle are increased by 4cm, the area is increased by 40cm, so what is the circumference of the original rectangle?

Let length x and width y, then perimeter 2x + 2Y (x + 4) * (y + 4) = XY + 40 XY + 4x + 4Y + 16 = XY + 40 4x + 4Y = 24 2x + 2Y = 12 and perimeter 12cm

The circumference of a rectangle is 40 cm. If the length and width are increased by 5 cm, how many square centimeters will the area be increased

Let the length be a and the width be B
So a + B = 40 / 2 = 20 cm, s = ab
Let the length of 5 cm be A1 = a + 5, and the width of 5 cm be B1 = B + 5
So the changed area is S1 = (a + 5) (B + 5) = AB + 5 (a + b) + 25 = S + 5x20 + 25 = S + 125
That is, s1-s = 125
So the area is increased by 125 square centimeters

What is the area of a rectangle if its perimeter increases by 20% and its width decreases by 20%

The title should be "long" increased by 20%
Now the area of rectangle is: (1 + 20%) (1-20%) = 1.2 × 0.8 = 0.96
Now the area of the rectangle is 96% of that of the original rectangle