The diameter of the bottom of the fountain is 8 meters. How many cubic meters of concrete is needed to build a concrete path with a width of 1 meter and a thickness of 20 cm along the fountain?

The diameter of the bottom of the fountain is 8 meters. How many cubic meters of concrete is needed to build a concrete path with a width of 1 meter and a thickness of 20 cm along the fountain?

8 △ 2 = 4m
4 + 1 = 5m
20 cm = 0.2 M
3.14 × (5 & # 178; - 4 & # 178;) × 0.2 = 5.652 m3

A cylindrical spray tank, with an inner diameter of 8m, can hold up to 25.12m3 of water. How many meters deep is the tank?

25.12 ^ [3.14 × (8 ^) 2] = 25.12 ^ 50.24 = 0.5 (m) a: the depth of the pool is 0.5 m

For a circular fountain with a radius of 16 meters, a circular flower belt with a width of 1 meter should be built around it. For example, 32 flowers are planted per square meter, and each flower costs 4.5 yuan. How many yuan should this circular flower belt invest at least?

The radius of inner circle is 16m, the radius of outer circle is 16 + 1 = 17m, 3.14 × (172-162) × (32 × 4.5), = 3.14 × (289-256) × 144, = 3.14 × 33 × 144, = 14921.28 yuan; a: the investment of this ring flower belt is at least 14921.28 yuan

There is a circular fountain with a diameter of 18 meters in the square. A one meter wide road is built around the fountain. What is the area of this road?

18 / 2 = 9m
9 + 1 = 10m
3.14*10*10-3.14*9*9
=3.14*19
=59.66 square meters

People's square has a round fountain, the diameter of which is 8 meters. The lane around the fountain is 1 meter wide. What's the area of the lane

Consider the area difference between two circles
The radius of the small circle is 4 and the area is 16 π
The radius of the big circle is 1 more than that of the small circle, with a radius of 5 and an area of 25 π
The area of the path is 25 π - 16 π = 9 π
If it's not clear, hi, I

The diameter of a circular fountain is 6 meters. Now we need to build a 1 meter wide cement road around the fountain. What is the area of the cement road?

The analysis shows that the distance from the outermost roadside to the center is 3 + 1 = 4m by building a 1m wide cement pavement around the fountain
It can be seen as two concentric circles, one with a radius of 3 meters and the other with a radius of 4 meters. The area of the middle ring is water
Area of dirt road
Solution: 3.14 times 4 ^ 2-3.14 times 3 ^ 2 = 21.98 square meters
So the area of cement road is 21.98 square meters

The diameter of a circular fountain is 6 meters. Now we need to build a 1 meter wide cement pavement around the fountain. What is the area of the cement pavement?

6 △ 2 = 3M
The area of cement pavement is 3.14 × 4 × 4-3.14 × 3 × 3 = 21.98m;

In front of the mall building, build a cylindrical fountain with a diameter of 8 meters and a depth of 1.8 meters. Plaster a layer of cement around and at the bottom of the fountain. What is the area of the cement plastering part in square meters?

From the meaning of the title
The place in the figure is the sum of the surface areas of the cylinders
Surface area 3.14 * 8 * 1.8 = 45.2
Bottom area 3.14 (8 / 2) ^ 2 = 50.24
So the area of cement in the figure is 45.2 + 50.24 = 95.44

A fountain with a radius of 8 meters is surrounded by a 1 meter wide cement road. What is the area of this cement road?
There should be a formula

(9*9-8*8)*3.14=53.38

A cylindrical fountain, bottom diameter of 4 meters, 1.5 meters deep, with cement painting pool, need to paint the area is how many square meters

Angela, Jane,
The bottom area is:
3.14 × (4 △ 2) ^ 2 = 12.56 (M2)
The lateral area is:
3.14 × 4 × 1.5 = 18.84 (M2)
Need painting:
12.56 + 18.84 = 31.4 (M2)