Graphic classification: a square, a rectangle, a cylinder, a triangle, a circle, there are several classification methods, how to divide

Can be divided into: 1 solid graphics: cylinder
2 plane figure: square, rectangle, triangle, circle
Plane graphics can be divided into: ① polygon: square, rectangle, triangle
② Circle

There are several ways to place squares, triangles, circles and five pointed stars in a square and make only one figure appear in each row and column
There are four lines in the square, four in each line, and 16 in total

Is there an answer? Is it 576
Idea: select 4 positions in the grid. Select 1 position in the first column, there are 4 methods; select again in the second column, there are 3 methods to push down. A total of 4 * 3 * 2 * 1 = 24
Then put different patterns on the selected position. 4 methods
So the answer is 24 * 4! = 576

The figure shows three views of a machine part. (1) please write the name of the geometry that conforms to the shape of the machine part; (2) if the triangle in the top view is an equilateral triangle, then please calculate the surface area of the geometry (unit: cm2) according to the dimensions marked in the figure

(1) The geometry conforming to this part is a straight triangular prism; (2) ∵ △ ABC is an equilateral triangle, and ∵ CD ⊥ AB, CD = 23, ∵ AC = cdsin60 ° = 4, ∵ s surface area = 4 × 2 × 3 + 2 × 4 × 12 × 23, = 24 + 83 (cm2)

Draw a similar figure of a known triangle ABC with respect to point O. the ratio of the new figure to the original figure is 2:1

Drawing method:
1. Connect OA and extend to D to make ad = 2oa;
2. Connect OB and extend it to e so that be = 2ob;
3. Connect OC and extend to f to make CF = 2oC;
4. Connect De, EF and FD, then △ DEF is the triangle

Can we prove that these two triangles are similar figures?

Yes
There is a theorem that if two angles are equal, triangles are similar

In the following groups of figures, the one that must be similar is that a has one side and the height on this side corresponds to two triangles in proportion, and B has two sides and the height on the third side
The middle line corresponds to two proportional triangles C, two isosceles trapezoids d with the bottom angle of 45 degrees and two right angled trapezoids d with the angle of 60 degrees

Why not choose C?

5. There is rice in one area, 40% in one week, 12 kg in two weeks, and 6 kg left. How many kg of rice is this bag?
6. A cylindrical steel with a volume of 75306 cubic centimeters is fused into a cone model with a bottom diameter of 4cm. What is the height of the cone model?

(12 + 6) / (1-40%) = 18 / 0.6 = 30 (kg)
75306 * 3 / (π * 2 * 2) = 17987 (CM)

In the first half of 2006, the number of mobile phones sold by the mobile sales department was 2000, 2200, 2500, 2800 and 3000 respectively. How many mobile phones were sold each month on average? What percentage of the sales in the second quarter was more than that in the first quarter? (one decimal place before the percent sign)

Average monthly sales of mobile phones
(2000 + 2200 + 2500 + 2500 + 2800 + 3000) △ 6 = 2500 (unit)
First quarter sales
2000 + 2200 + 2500 = 6700 (units)
Second quarter sales
2500 + 2800 + 3000 = 8300 (units)
More sales in the second quarter than in the first
（8300－6700）÷6700＝23.9％

The standard of electricity charge in a city is as follows: charge 0.5 yuan per kilowatt hour if the electricity consumption point is within 50 degrees (including 50 degrees), charge 0.45 yuan per kilowatt hour if the electricity consumption exceeds 50 degrees per month, and charge 3.3 yuan less than that of Li family in a month. How many kilowatt hours do Wang family and Li family use?
I can't understand it. Can it be simpler,

It's just a word. I'll say it only once
But I still want to give you an answer in 500 years
The standard of electricity charge in a city is as follows: if the monthly electricity consumption is within 50 degrees (including 50 degrees), it will be charged at 0.5 yuan per degree; if the monthly electricity consumption exceeds 50 degrees, it will be charged at 0.45 yuan per degree. The electricity charge paid by Wang family is 3.3 yuan less than that of Li family. How many degrees of electricity will Wang family and Li family use?
First, if the power of the two companies is below 50 degrees, the difference between their money should be yuan or 0.5 yuan, which is not consistent with 3.3 yuan
Second, if both of them are above 50 degrees, the difference between them should be 3.3/0.45 = 7.33 degrees, which is not an integer and does not conform to the question
Well, it shows that one of them is below 50 degrees and the other is above 50 degrees
Let Wang's power be x and Li's power be y
50*0.5+[Y-50]*0.45=X*0.5+3.3
9Y-10X=16
Y=16/9+10X/9>=50
X>=43.4
Because XY is an integer and 16 / 9 = 1.7
Then the remainder of 10x / 9 is 2
So x = 47
Y=54
A: the Wang family's electricity consumption is 47 degrees, and the Li family's is 54 degrees
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I'm in Grade 6, too~

How to do questions 4 and 6 of the application questions on page 22 of the test paper of primary school mathematics ability
A. B the distance between the two places is 540 meters. If the speed ratio between a and B is 5: how many meters per minute do a and B travel?
The kindergarten bought 40 blankets of different sizes for a total of 3200 yuan. The unit price of the big blanket is 11 yuan more than twice that of the small blanket. How much is the single price of the two kinds of blankets?

540 △ 5 = 108m
Speed of a: 108 × 5 / (5 + 4) = 60m / min
Speed of B: 108 × 4 / (5 + 4) = 48 m / min

Graphic classification: a square, a rectangle, a cylinder, a triangle, a circle, there are several classification methods, how to divide