The length of the three wires is 215 meters. One third of the first wire is used, three fifths of the second wire is used, and three fourths of the third wire is used How long are the three wires?

First: 215 times 1 / 3 = 215 / 3M second: 215 minus 215 / 3 = 430 / 3 430 / 3 times 3 / 5 = 86m third: 430 / 3 minus 86 = 172 / 3 172 / 3 times 3 / 4 = 43M

A rectangular desktop is 7 / 8 meters long and 3 / 4 meters wide, and the other square desktop is 7 / 8 meters long. Which desktop area is larger? How much?

The square table covers an area of 5 / 64 square meters

When vegetable farmers grow vegetables in plastic greenhouses, why not use green plastic film as greenhouses

If you use green, you can only let green light in. It seems that plants need red light most

There are 27 greenhouses in the greenhouses vegetable base, each of which can produce 140 kg of vegetables in the first quarter on average. How many kg of vegetables do these greenhouses produce in a year?

140x4x27
=15120kg
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As shown in the figure, to build a seedling shed, the height of the shed H = 1.8 & nbsp; m, the width of the shed a = 2.4 & nbsp; m, the length of the shed is 12 & nbsp; m, now to cover the plastic film on the top of the shed, how many square meters of plastic film do you need?

∵ H = 1.8 m, a = 2.4 m, ∵ AB = A2 + H2 = 3 (m), ∵ AB = 3M, ∵ the area of rectangular plastic film is 3 × 12 = 36 (M2)

As shown in the picture, Uncle Wang is going to build a vegetable shed, which is 8m wide, 6m high and 20m long. The slope of the shed is covered with plastic film. Regardless of the thickness of the wall, please calculate the maximum area of sunlight

According to the Pythagorean theorem, the width of the slope of the vegetable greenhouse, that is, the length of the slope of the right triangle, is 62 + 82 = 10m, so the slope area of the vegetable greenhouse is 10 × 20 = 200m2

Uncle Zhang wants to replace the plastic film for the vegetable greenhouse at home. It is known that the greenhouse is 18 meters long and 6 meters wide, and the cross section is a semicircle. How many square meters of plastic film is needed to cover the vegetable greenhouse?

[3.14 × (6 △ 2) 2 × 2 + 3.14 × 6 × 18] △ 2 = (56.52 + 339.12) △ 2 = 395.64 △ 2 = 197.82 (square meters) a: it needs 197.82 square meters of plastic film to cover the vegetable greenhouse

To build a vegetable greenhouse, the width is 3.2 meters, the length is 4 meters, and the length is 15 meters
In five minutes

It should be the surface area of the cube with the bottom removed
3.2 * 2.4 * 2 + 3.2 * 15 + 2.4 * 15 * 2 = 135.36 (M2)

Xiao Li is going to build a vegetable greenhouse with width of 4, height of 3 and length of 20. The slope of the greenhouse is covered with plastic film. Please calculate the area of plastic film

That is to find the area of the rectangle with two inclined planes
Oblique side length = under radical (2 & sup2; + 3 & sup2;) = 13 under radical
Plastic film area = 2 × 20 × 13 under root
=40 times root 13

As shown in the picture, a vegetable greenhouse covered with plastic film is 20 meters long and its cross section is a semicircle with a radius of 2 meters
The final result is 80 square meters

Area 2x20 = 80 square meters
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The length of the three wires is 215 meters. One third of the first wire is used, three fifths of the second wire is used, and three fourths of the third wire is used How long are the three wires?