In school, I can see the children's bright smile and the sound of reading every day

In school, I can see the children's bright smile and the sound of reading every day

In school, we can see the children's bright smile and hear the sound of reading every day
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Does Lang Lang write like this in his reading voice?

Both Lang Lang and Lang Lang can be used. It's just that Lang Lang reads three tones and Lang Lang reads two

When I walked into the school gate, I saw the students in activities and the sound of reading

Lang Lang's reading voice is not heard, so it should be changed to: I walked into the school gate, saw the students in the activities and (heard) Lang Lang's reading voice

The circumference of a rectangle is 24 cm. If the length of the rectangle decreases by 1 cm and the width increases by 2 cm, it becomes a square. Find out the length of the rectangle
Let the equation of one variable be of one degree

Let the length of the original rectangle be x cm and the width be (24 △ 2-x) cm
x-1=(24÷2-x)+2
x-1=14-x
x+x=14+1
2x=15
x=7.5
The width of the rectangle is: 12-7.5 = 4.5 (CM)

The average speed of an object moving in a straight line at a constant speed over a period of time is equal to the speed at the middle of the time,

Yes, it's a corollary, but it has to be uniform! You can see it from the V-T image
Since it is uniform, then the V-T image should be an inclined straight line, V and t is a linear function, so the midpoint of a period of time must correspond to the midpoint of the speed!
Let's write down some inferences about the average speed, only for uniform speed change!
v=x/t
=VT / 2 (T / 2 is the right subscript, i.e. the middle time)
=(VO + VT) / 2 (1 / 2 of the sum of initial velocity and final velocity in a period of time)

2x^4-3x^2+5x-3=( )-3x^2+5x=( )-3x^2-5x

2x^4-3x^2+5x-3=(2x^4-3)-3x^2+5x=(2x^4+10x-3)-3x^2-5x

The height of a cylinder is 6cm. Its side view is a sector with a radius of 10cm and a central angle of 216 degrees. What is the volume of a cone

The radius of the side view is 10 cm, and its arc length is: π (PIE) * 10 * 2 * 216 ° / 360 ° = 12 π (CM)
12 π is the circumference of the base circle, so the radius of the base circle is: 12 π / 2 π = 6 (CM)
The volume is 1 / 3 * π * 36 * 6 = 72 π (cm2)
By the way, you have the wrong number~

As shown in the figure, given that the point E is on the straight line DF and the point B is on the straight line AC, if ∠ AGB = ∠ EHF. ∠ C = ∠ D, is ∠ a equal to ∠ f? Why?

The reason is: ∵ AGB = ∵ EHF, ∵ AGB = ∵ DGH, ∵ EHF = ∵ DGH, ∥ BD ∥ CE, ∵ C = ∥ abd, and ∵ C = ∵ D, ∵ abd = ∥ D, ∥ AC ∥ DF, ∥ a = ∥ F

The problem of mathematical absolute value inequality
If real numbers x and y satisfy │ cosx cosy │ = │ cosx │ + cosy │, and X ∈ (π / 2, π), then √ (cosx + cosy) ^ 2 is equal to

From X ∈ (π / 2, π), we can deduce that cosx = 0
And because │ cosx cosy │ = cosx cosy or cosy cosx
Therefore, we will launch: cosx cosy = | cosy | - cosx = cosy cosx launch cosy > 0 > cosx > - cosy
So cosx + cosy > 0
√(cosx+cosy)^2=cosx+cosy

It is known that the circumference of a semicircle is 10.28cm. Do you know its radius?

It is known from the title that the circumference of a circle is 10.28 × 2 = 20.56, radius r = 20.56 △ 2 △ Π≈ 3.27