3 practical questions, How many times can a 1570cm copper wire be wound on a circular coil with a radius of 2-5cm? Use a rectangular sheet of iron 2 cm long and 7 cm wide to cut a disc. The radius of the disc is 1.5 cm. How many can you cut? How many square meters is the area of a semicircular duck farm surrounded by a 12.56-meter-long fence? The radius of the copper wire is 2.5cm. dial the wrong number

3 practical questions, How many times can a 1570cm copper wire be wound on a circular coil with a radius of 2-5cm? Use a rectangular sheet of iron 2 cm long and 7 cm wide to cut a disc. The radius of the disc is 1.5 cm. How many can you cut? How many square meters is the area of a semicircular duck farm surrounded by a 12.56-meter-long fence? The radius of the copper wire is 2.5cm. dial the wrong number

1. Consider the radius of copper wire (assuming DCM)
1570÷3.141÷2÷(2.5+d)
God knows the answer
3,12.56=3.14r+2r
r=2.44358
Area = 3.14 × 2.44358 × 2.44358 △ 2 ≈ 9.37

If the side length of a square is increased by 2cm and the area is increased by 32cm2, then the side length of the square is ()
A. 6cmB. 5cmC. 8cmD. 7cm

Let the side length of the square be X. if the side length of the square is increased by 2cm, then it is x + 2. According to the meaning of the title, the equation is given as x2 + 32 = (x + 2) 2, and the solution is x = 7. Then the side length of the square is 7cm

Is the earth and the sun celestial bodies? What are celestial bodies
The earth and the sun are not celestial bodies. (this is the point)

The name of celestial body comes from people's wishful thinking of taking the earth as the center of the universe and turning objects beyond the earth into celestial bodies. I personally understand that

Ask two questions about scientific density calculation in grade two of junior high school
1. Frozen beer is, because it will burst. Xiao Ming explored this phenomenon. He used 450 cubic centimeters of water as his area, and the volume of frozen ice was 500 cubic centimeters. He asked what the density of ice was.
2. When a glass bottle with a mass of 0.25 kg is filled, the total mass is 1.5 kg. If the total mass of a liquid filled is 1.75 kg, what is the density of the liquid?

Question 1: because the density of water is known to be 1 gram per cubic centimeter, the density of ice is 1 times 450 and divided by 500, which equals 0.9 gram per cubic centimeter
The second question: first of all, you can convert the unit, 0.25 kg is equal to 250 grams, 1.5 kg is equal to 1500 grams, 1.75 kg is equal to 1750 grams, So a density of 1500 divided by 1250 is 1.2 grams per cubic centimeter

The perimeter of a circular flower bed is 37.68cm. What is the area of this flower bed? How many square meters does the path cover when a 1m wide path is paved around the flower bed?

Hello
Radius 37.68 ÷ (2x3.14) = 6M
Area 6x6x3.14 = 113.04 square meters
Path radius 6 + 1 = 7M
Area 7x7x3.14-6x6x3.14 = 40.82 M2
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I don't understand. I can ask
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How do you divide 7 by 14 out of 15

=7 times 15 / 14
=15 / 2
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Find the range of y = 1 + SiNx + cosx + sinxcosx

Let t = SiNx + cosx = 2Sin (x + π 4), then t ∈ [- 2, 2]. From (SiNx + cosx) 2 = T2 ﹥ sinxcosx = t2-12. ﹥ y = 1 + T + t2-12 = 12 (T + 1) 2. ﹥ ymax = 12 (2 + 1) 2 = 3 + 222, Ymin = 0. ﹥ the range is [0, 3 + 222]

The side length of a square is in direct proportion to its perimeter and area

Wrong
Only the perimeter is proportional

Two 3's and two 7's with appropriate symbols are equal to 24

（3+3÷7）×7=24÷7×7=24
In brackets is the sum of fractions, to divide

Given that the first term of {an} is 1, the common ratio is Q, and the sum of the first n terms is Sn, find LIM (Sn / Sn + 1)

(1) When q = 1, Sn = n; s (n + 1) = (n + 1)
lim（Sn/Sn+1）＝n/(n+1)＝1
(2) When q = - 1, n is even, Sn = 0; s (n + 1) = 1, limit = 0
N is odd, Sn = 1, s (n + 1) = 0, the limit does not exist;
(3) When Q ≠ ± 1:
Sn=a1·(1-q^n)/(1-q)
S(n+1)＝a1·[1-q^(n+1)]/(1-q)
Sn/S(n+1)＝(1-q^n)/[1-q^(n+1)]
∴lim（Sn/Sn+1）＝(1-q^n)/[1-q^(n+1)]
If | Q | > 1:
lim（Sn/Sn+1）＝lim(1/q^n -1)/[1/q^n-q]＝(-1)/(-q)＝1/q
If | Q|