Question

Периметр прямоугольника 40см.а сумма длин трех его сторон равна 28см.чему равна площадь этого прямоугольника?

Answer 1

40-28=12 одна его большая сторона
значит у него две стороны по 12, и две по 8см
площадь прямоугольника : S = ab
S=12*8=96квадратных см
площадь прямоугольника-96 квадратных сантиметров

Answer 2

Calculation of the Rectangle's Area

To find the area of a rectangle, we need to know the lengths of its sides. In this case, we are given that the perimeter of the rectangle is 40 cm and the sum of the lengths of three of its sides is 28 cm.

Let's assume the lengths of the three sides are a, b, and c. According to the given information, we have the equation:

a + b + c = 28 Since the perimeter of a rectangle is the sum of all its sides, we can express the perimeter as:

2(a + b) = 40 From these two equations, we can solve for a and b:

a + b = 20 (dividing both sides of the second equation by 2)

Substituting this value into the first equation:

(20 - c) + c = 28

Simplifying:

20 + c = 28

c = 8

Now that we know the value of c, we can substitute it back into the equation a + b = 20 to find the values of a and b:

a + b = 20

a + b = 20 - 8

a + b = 12

Since the rectangle has two pairs of equal sides, we can assume that a = b. Therefore, we have:

2a = 12

a = 6

b = 6

Now we know that the lengths of the sides of the rectangle are a = 6 cm, b = 6 cm, and c = 8 cm.

To find the area of the rectangle, we use the formula:

Area = length × width

Area = a × b

Area = 6 cm × 6 cm

Area = 36 cm²

Therefore, the area of the rectangle is 36 square centimeters.