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There are three lawns in the street garden. The first one accounts for 3 / 10 of the total area, the second one covers 1 / 5 of the total area, and the third one accounts for 1 / 3 of the total area. What is the total area of the three lawns in the street garden?
The answer is not necessarily right
There are three lawns in the street garden, with a total area of X hectares
10/3X+3/1X+5/1=1
X=19/24
The total area of the three lawns in the street garden is 19 / 24 hectare
1. The shadow part is the lawn, and the blank part is the path (there is a small circle in a big circle, the big circle is the blank part, and the small circle is the shadow part). Xiaodong walks along the outside of the path for 62.8 meters. The width of the road is known to be 1 meter, and the area of the lawn is calculated. 2. Xiaoxu draws two concentric circles with a compass. When drawing the first circle, the distance between the two feet of the compass is 3 cm, and the second circle is, He increased the distance between the two feet of the compass by 2 cm
1、
The radius of the big circle is
62.8÷（2×3.14）
=10 meters
The radius of the small circle is
10-1
=9 meters
The area of lawn is
3.14×9²
=254.34 square meters
2、
Circle area
3.14×（（3+2）²-3²）
=3.14×16
=50.24 square centimeter
In order to green the campus, the school decided to build a rectangular lawn, 30 meters long and 20 meters wide, and build a cross road on the lawn as shown in the figure. The width of the road is x meters, expressed by algebraic formula: (1) how many square meters is the area of the road? (2) What's the area of the lawn in square meters?
（1）30×20-（30-x）（20-x）=600-600-x2+50x=-x2+50x；（2）（30-x）（20-x）=600-50x+x2．
RELATED INFORMATIONS
- 1. As shown in the figure, the shaded part represents the campus lawn, the blank part represents the path, and the algebraic expression is used to represent the lawn area
- 2. In the "old city reconstruction" of a city, it is planned to plant turf on a triangular open space in the city as shown in the figure to beautify the environment Planting turf to beautify the environment is known to cost 80 yuan per square meter. How much does it cost to buy this kind of turf?
- 3. In the "old city reconstruction", a city plans to plant some kind of turf on a triangular open space as shown in the figure to beautify the environment. It is known that ab = 30m, AC = 40m, ∠ BAC = 150 ° and the price of this kind of turf is a yuan per square meter. How much is it required to buy this kind of turf at least?
- 4. Can 15 meters, 16 meters and 17 meters form a triangle? What's the area?
- 5. The area of the trapezoid is 2 hectares. How many meters is the bottom of the trapezoid
- 6. If the side length of a square garden covering 4 hectares is reduced by 10 meters, how many square meters will the area of the garden be reduced
- 7. A trapezoidal vegetable field, with an area of 270 square meters, has a top bottom of 28 meters and a bottom of 32 meters. How high is it
- 8. The area of a trapezoidal orchard is about 2.4 hectares. Its top bottom is 320 meters long and its bottom is 180 meters long. How high is the trapezoidal orchard?
- 9. There is a square orchard covering an area of 1 hectare. If its sides are extended by 200 meters, how many hectares will the area of the orchard increase?
- 10. There is a rectangular wheat field, 900 meters long and 400 meters wide, with a total yield of 194400 kg of wheat. How many kg of wheat are harvested per hectare on average?
- 11. There is a triangle lawn in the middle of the road (see photo). The price of 1 m2 lawn is 12 yuan. How much does it cost to grow this lawn?
- 12. Pythagorean theorem] if the length of the hypotenuse of an isosceles right triangle is 4, then the perimeter of the right triangle is 4 It's a process
- 13. The perimeter of a rectangular lawn is 36m. If its length and width increase by 3M, how many square meters will the original lawn area increase?
- 14. The perimeter of a rectangular lawn is 36m. If its length and width increase by 3M, how many square meters will the original lawn area increase?
- 15. As shown in the figure, to build a lawn with equal radius at each of the three corners of the triangle square ABC, the radius of the fan should be 20 meters, and the total area of the lawn should be calculated. (π = 3.14)
- 16. A school takes an equilateral △ ABC corner with a side length of 2A The corner of an equilateral △ ABC with a side length of 2a is divided into two parts with equal area by de. D is on AB and E is on AC (1) Let ad = x (x ≥ a), ed = y, find the functional relation of Y expressed by X;? (2) If De is the location of irrigation water pipe, in order to save money, I hope it is the shortest, where should de be? If De is the tour line, I hope it is the longest, where should de be? The answer is (1) y = √ (x ^ + 4 * (a ^ 4) / x ^ - 2A ^) (2) When ad = (√ 2) * A and de ‖ BC, De is the shortest; when D is the midpoint of AB, e coincides with C or D coincides with B, e is the midpoint of AC, De is the longest Mainly the first question
- 17. A rectangular grassland is 16 meters long and 8 meters wide, with a stone road in the middle. If it costs 40 yuan to pave a 1 square meter grassland, how much does it cost to pave this land The back is the floor. How much is it?
- 18. The perimeter of a circular lawn is 37.68 meters, and a 2-meter-wide circular gravel road is paved outside. How many square meters is the area of this gravel road?
- 19. As shown in the figure, a trapezoidal Street garden is divided into two parts: parallelogram and triangle. Peony and rose are planted respectively. Peony covers an area of 300 square meters, and rose covers an area of how many square meters?
- 20. There is a vegetable plot with an area of 500 square meters, 1 / 3 eggplant, 2 / 5 cucumber and the rest tomato. How many square meters of tomato?