Question

Бак имеет форму параллелепипеда длиной 90см,шириной 50см,высотой 70 см.Бак надо покрасить снаружи и изнутри.Какую площадь надо покрасить?

Answer 1

90*50*2=9000(см в квадрате)-2 стороны
2)50*70*2=7000(см в квадрате)-еще 2 стороны
3)90*70*2=12600(см в квадрате)-еще 2 стороны
4)(12600+7000+9000)*2=28600*2=57200(см в квадрате)-надо покрасить
5)57200см=572дм
Ответ:572 дм

Answer 2

Calculation of the Surface Area of the Tank

To calculate the surface area of the tank, we need to find the area of each of its six faces and then sum them up.

The tank has the shape of a rectangular parallelepiped with the following dimensions: - Length: 90 cm - Width: 50 cm - Height: 70 cm

To find the surface area, we need to calculate the area of each face and then add them together.

Calculation of the Area of Each Face

1. Top and bottom faces: - The top and bottom faces of the tank have the same dimensions, so we only need to calculate the area of one of them. - The area of a rectangle is given by the formula: Area = Length x Width. - Therefore, the area of the top and bottom faces is: 90 cm x 50 cm = 4500 cm².

2. Front and back faces: - The front and back faces of the tank have the same dimensions, so we only need to calculate the area of one of them. - The area of a rectangle is given by the formula: Area = Length x Height. - Therefore, the area of the front and back faces is: 90 cm x 70 cm = 6300 cm².

3. Side faces: - The tank has two side faces with the same dimensions, so we only need to calculate the area of one of them. - The area of a rectangle is given by the formula: Area = Width x Height. - Therefore, the area of the side faces is: 50 cm x 70 cm = 3500 cm².

Calculation of the Total Surface Area

To find the total surface area, we add up the areas of all six faces of the tank:

- Top and bottom faces: 4500 cm² + 4500 cm² = 9000 cm² - Front and back faces: 6300 cm² + 6300 cm² = 12600 cm² - Side faces: 3500 cm² + 3500 cm² = 7000 cm²

Therefore, the total surface area of the tank that needs to be painted is:

9000 cm² + 12600 cm² + 7000 cm² = 28600 cm².

So, you would need to paint a surface area of 28600 cm² on the tank, both on the outside and inside.