How many square meters is one foot

Ancient times "the cloth finger knows the inch, the cloth hand knows the ruler"
In the Shang Dynasty, one foot is 16.95cm. According to this scale, the height of a person is about one foot, so it is called "husband"
In the Zhou Dynasty, one foot is 23.1cm
In Qin Dynasty, one foot was about 23.1cm
In Han Dynasty, one foot was about 21.35-23.75cm
Three Kingdoms, one foot is 24.2cm
In the Southern Dynasties, one foot is about 25.8cm
In the Northern Wei Dynasty, one foot is 30.9cm
In Sui Dynasty, one foot is 29.6cm
In Tang Dynasty, one foot is 30.7cm
In the song and Yuan Dynasties, one foot was 31.68cm
In the Ming and Qing Dynasties, woodworking was 31.1cm,

1. The average length of the top and bottom of a trapezoid is 42 cm, and the height is 24 cm. Find the area of the trapezoid

As shown in the figure, △ ABC is known. Take AB and AC as the edges to make equilateral triangle abd and equilateral triangle ace outward respectively. M is the midpoint of AD, n is the midpoint of AE, and P is the midpoint of BC
When the angle BAC = 90 °, calculate the angle MPN =?
If the triangle ABC is any triangle, find the degree of ∠ MPN

Extend EA to intersect BD and K. according to the similarity, it is proved that AC: ab = 1: radical 3, angle ABC is equal to 30 ° and triangle NPC congruence and triangle PAM, so angle MPN = 60

Let's know the third power of 2A + the fifth power of m power B - the fourth power of 9a, the nth power of B + the fifth power of 1 = - 7a, and find the n power of (- 2m + n)

Let's know the third power of 2A + the fifth power of m power B - the fourth power of 9a, the nth power of B + the fifth power of 1 = - 7a, and find the n power of (- 2m + n)
∴3+m=4；
n+1=5；
∴m=1;
n=4;
∴(-2m+n)^n
=(-2+4)^4
=16;
I'm very glad to answer your questions. Skyhunter 002 will answer your questions
If you don't understand this question, you can ask,

What is missing the stars and the moon

Miss the stars and the moon, miss the bus and the next train, miss the lover will have, tell us not to be too persistent, too negative, Miss missed, it's no big deal, life still need to continue to be strong. In fact, life only constantly miss to become wonderful

1. (1) in order to prove that sodium hydroxide solution has been deteriorated by experimental method, a small amount of sodium hydroxide solution can be put into a test tube, and a small amount of () solution can be dropped. The phenomenon observed is (), which proves that sodium hydroxide solution has been deteriorated. Write out the chemical equation of the reaction ()
(2) How to remove the impurities in the sodium hydroxide solution (briefly write the test method and the chemical equation of the reaction)?

Generally speaking, the impurity in NaOH refers to Na2CO3 (sodium carbonate), which is caused by the effect of NaOH and CO2 in the air. Therefore, as long as an appropriate amount of HCl is added: Na2CO3 + HCl = NaCl + H2O + CO2

If 2x ^ 3-x ^ 2-13x + k is divisible by 2x + 1, then K is ()

2x^3-x^2-13x+k
=x^2(2x+1)-2x^2-13x+k
=x^2(2x+1)-x(2x+1)-12x+k
=x^2(2x+1)-x(2x+1)-6(2x+1)
k=-6

1: Rectangular swimming pool, 50 meters long and 30 meters wide. Choose scale () to draw the largest plan, choose scale () to draw the smallest
A：1：1000 B：1：1500 C：1：500 D：1：100
2: The distance between Nanjing and Shanghai is 200 km. Measured on a map, the distance between them is 20 cm. The scale on the map is ()
A：1：1000000 B：1：100000 C ：1：10 D：1000000：1
3: To build a factory building 40 meters long and 20 meters wide, we need to draw () cm long on the drawing with a scale of 1:500?
A ：5 B：8 C：7 D：6
4: On a drawing, a 6 cm line segment represents 3 mm. The scale of this drawing is ()
1：20 1：20 20：1 2：1
5: On a map with a scale of 1:1000000, use () to represent 60 kilometers
0.6cm 6cm 60cm 600
6: A round flower bed is drawn on the drawing after being reduced by 1:100, with a diameter of 2cm. The actual floor area of the flower bed is () square meters?
6.28 628 3.14 314
7: A plane from Nanning to Zhengzhou, flight speed and time ()
The proportion is positive, the proportion is negative, the proportion is not certain

1: Rectangular swimming pool, 50 meters long and 30 meters wide. The plan drawn by scale (d) is the largest, and the plan drawn by scale (b) is the smallest
A：1：1000 B：1：1500 C：1：500 D：1：100
2: The distance between Nanjing and Shanghai is 200 km. Measured on a map, the distance between them is 20 cm. The scale on the map is (a)
A：1：1000000 B：1：100000 C ：1：10 D：1000000：1
3: To build a 40 meter long and 20 meter wide factory building, the scale is 1:500, the length should be (b) cm?
A ：5 B：8 C：7 D：6
4: On a drawing, a 6 cm line segment represents 3 mm. The scale of this drawing is (c)
A：1：20 B：1：20 C：20：1 D：2：1
5: On a 1:1000000 scale map, use (b) for 60 kilometers
A：0.6cm B：6cm C：60cm D：600cm
6: A round flower bed is drawn on the drawing after being reduced by 1:100, with a diameter of 2cm. The actual floor area of the flower bed is (c) square meters?
A：6.28 B：628 C：3.14 D：314
7: A plane from Nanning to Zhengzhou, flight speed and time (b)
A: Positive proportion B: negative proportion C: out of proportion D: not sure

Interesting experimental composition 400 words

This afternoon, the first class is science. We did the experiment of metal expansion and contraction
The experiment should be prepared: a basin of water, a copper ring, a copper ball, an alcohol lamp, and a lighter. The teacher first opens the cover of the spirit sprinkling lamp, and then uses a lighter to light the alcohol lamp, The teacher said to us, "did the copper ball pass through the copper ring?" we said with one voice, "just passed." then the teacher put the copper ball on the alcohol lamp to burn. After more than ten minutes, the teacher put the copper ball into the middle of the copper ring, but the copper ball couldn't pass. The teacher put the copper ball into the water basin again, The teacher put the copper ball in the middle of the copper ring, but it passed again. The teacher took the cover of the alcohol lamp and obliquely put out the alcohol lamp. Everyone was puzzled. The teacher explained: "the first time, the copper ball just passed, but the second time, because the volume of the copper ball burned on the alcohol lamp expanded, so it couldn't pass. The third time, I put the copper ball in the water, When a copper ball is cooled by water, its volume will shrink and it can pass through. This is the reason why metals expand and contract when they are heated. "The teacher also said," in addition to copper, many other objects will expand and contract when they are heated. For example, thermometers are made by this principle. "
It's really an interesting experiment. I not only know the heat and cold shrinkage of metal, but also know its great use

The sum of the squares of two consecutive even numbers is 20, and these two numbers are___
It is known that a factory plans to increase the annual output of a certain product from 1 million units to 1.21 million units in two years, so the average annual growth rate is about 10%

（2a)²+(2a+2)²=20
4a²+4a²+8a+4=20
a²+a-2=(a+2)(a-1)=0
a=-2,a=4
2 and 4 or - 4 and - 2
100(1+x)²=121
(1+x)²=1.21
1+x=1.1
x=10%

How many square meters is one foot