The focal length of the ellipse {x = 4 + 2cos θ, y = 1 + sin θ} (with θ as a parameter) is The focal length of the ellipse ({x + OS} = 4, θ = 1) I know the parametric equation of ellipse {x = ACOS φ, y = bsin φ} (φ is a parameter), so what do 4 and 1 in the question mean? What is the generalization to the general elliptic equation? A.√21 B.2√21 C.√29 D.2√29

4 and 1 in the question mean that the center of the ellipse is (- 4, - 1)
For example: an ellipse (x-m) ^ 2 / A ^ 2 + (y-n) ^ 2 / b ^ 2 = 1
This ellipse, with its center at (m, n), has the parameter equation {x = ACOS φ + m, y = bsin φ + n} (you can substitute these two numbers into the elliptic equation, and the left and right are equal)
It is equivalent to translating an ordinary ellipse, so the focal length, major axis, minor axis and eccentricity are all unchanged
So the centrifugation rate is √ 3-2
Shift term, x-4 = 2cos, Y-1 = sin θ, i.e. (x-4) ^ 2 / 4 + (Y-1) ^ 2 = 1, so a = 2, B = 1, C = root sign 3 is to extend the constant in the equation to the left, change it to x-m = ACOS φ, y-n = bsin φ, and then treat it as {x = ACOS φ, y = bsin φ}, which is actually the ellipse after translation
The center is not a dot
cos²θ+sin²θ=1
(x-4)²/4+(y-1)²=1
So the center is (4,1)
Move it four to the left and one down
It's X & sup2 / 4 + Y & sup2; = 1
So C & sup2; = 4-1 = 3
Focal length = 2C = 2 root sign 3
Use X to represent sin θ and y to represent cos θ. According to the sum of the squares of cos θ and sin θ is 1, we can get the relationship between X and Y. after getting the relationship, we can know what 4 and 1 mean
Given the ellipse {x = 2cos θ, y = sin θ (θ is a parameter) 1. Find the focus coordinate and eccentricity of the ellipse
Given the ellipse {x = 2cos θ, y = sin θ (θ is a parameter) 1. Find the focus coordinate and eccentricity of the ellipse; 2. Given that point P is any point on the ellipse, find the maximum distance PM between point P and point m (0,2)
∵x=2cosθ y=sinθ
From cos & # 178; θ + Sin & # 178; θ = 1, X & # 178; / 4 + Y & # 178; = 1
∴a=2 b=1,c=√3
∴e=c/a=√3/2
|PM²|=(2cosθ-0)²+(sinθ-2)²=4cos²θ+sin²θ-4sinθ+4=4(1-sin²θ)+sin²θ-4sinθ+4=-3sin²θ-4sinθ+8
=-3(sinθ+2/3)²+28/3
When sin θ = - 2 / 3, the maximum value of | PM | is √ (28 / 3) = 2 √ 21 / 3
The focus is (± √ 3,0), the eccentricity is √ 3 / 2, and the maximum distance is 4
1. A = 2, B = 1, C = (a ^ 2-B ^ 2) ^ 1 / 2 = √ 3, focus coordinate F1 (- √ 3, 0) F2 (√ 3, 0), eccentricity e = √ 3 / 2
2、M(0，2)
Ellipse x ^ 2 + 4Y ^ 2 = 4, let m be the center of the circle equation: x ^ 2 + (Y-2) ^ 2 = R ^ 2
That is to find the maximum value of R.
The simultaneous elimination of X gives R ^ 2 = - 3Y ^ 2 - 4Y + 8 (- 1)
Find the focal length of the ellipse x = 2cos θ, y = sin θ (where θ is a parameter)
2y=2sinθ
Square x ^ 2 + 4Y ^ 2 = 4, that is x ^ 2 / 4 + y ^ 2 = 1
So a ^ 2 = 4, B ^ 2 = 1, so C = √ 4-1 = √ 3
So the focal length 2C = 2 √ 3
Conversion relationship between power and kilovolt ampere
Generally, KVA is one size larger than kW, for example, the power output of 0.75KW is 1.1kva, 5.5kW is corresponding to 7.5kVA, KVA * power factor = kW, and the general power factor is between 0.88-0.95
The working current of LCD electronic calculator is about 120 μ A. 120 μ a = how many Ma = how many a

A project is divided into two groups: the first group of 19 people dug 41.2 meters in three days, and the second group of 25 people dug 55.1 meters in three days. According to this schedule, how many days will it take to complete a 560 meter long tunnel?
560 / (41.2 / 3 + 55.1 / 3) = 560 / [(41.2 + 55.1) / 3] = 560 / 32.1, about 17.5 days
(55.1+41.2)/3=32.1
560/32.1=17.4=18
The sum of 560 divided by 41.2 + 55.1 is about 6
This question gives the work efficiency and the total amount of work, find the working time. Then divide the total amount by 560 of their work efficiency and, then you can get the answer
18 days
1. Arithmetic
① Step by step calculation
41.2 / 3 + 55.1 / 3 = 32.1 (m)
560 / 32.1 ≈ 18 (days)
② Synthesis algorithm
560/[（41.2+55.1）/3]
=560/[96.3/3]
=560/32.1
About 18 (days)
2. Equation
It takes X days to complete
(41.2/3+55.1/3)x=560
32.1x=560
What day do you want to visit the museum? Xiao Hong's mother works for 4 days and has 1 day off. Xiao Hong's father works for 2 days and has 1 day off. Xiao Hong has Saturdays and Sundays off. Xiao Hong, her mother and her father work for 2 days; Xiao Hong, her mother and father will have a rest on July 3. They will go to see their grandfather together. They will visit the museum on the next day when they have a rest at the same time. What's the date of visiting the museum?
The least common multiple of 3 and 5 is 15, 2 + 15 = 17, July 17 is Sunday, that is, they have a rest to visit the museum on July 17
How to convert the power of an air conditioner, such as how many kilowatts is a horse?
1p power is 735w, cooling capacity is 2200W. 1.5p power is 1.5 * 735 = 1102.5w, cooling capacity is 3 * 1102.5 = 3307.5w
Is the molecular hypothesis of ampere ring current correct?
There are two concepts for you: 1. No hypothesis is absolute truth, and every proposition has extension (temporarily can be understood as the scope of use) and connotation. Moreover, the progress of human science is a process of proving whether or not. When a phenomenon occurs, it is correct to put forward a hypothesis to explain it, which can explain it and does not violate the existing understanding. When people's level of understanding is higher, To prove that this hypothesis is not completely correct (to prove it or not) is the progress of science. Therefore, the correctness of Ampere's electron flow hypothesis refers to the hypothesis of explaining electromagnetic relations in the context of his scientific era. It is correct in explaining some phenomena, just like no one can measure the true height of a table, No matter how accurate the instrument is, it can only add a few more digits after the decimal point, but it can't say that the next digit will be gone. It's just that I don't have the same applicable environment. For example, when we make ordinary tables, it is considered correct to be accurate to millimeter. Even the hypothesis put forward by contemporary scientists can't be said to be absolute truth. If someone says it, he is not a scientist, It should be religious. 2. The image description of probability density distribution of electron cloud in the space outside the atomic nucleus. The possibility of electron appearing in a certain area outside the atomic nucleus is composed of hundreds of photos of the position of electron appearing, which indicates the probability of electron appearing in these spaces. There is no theory to show that electron jumps in the form of electron cloud
How to add, subtract, multiply and divide four 7S
（7/7）+(7/7)=2
7/7+7/7=2
(8-(8÷8)÷8)×8=88 (8-((8÷8)÷8))×8=88 (8-(8÷8)÷8)×8=88 (8-((8÷8)÷8))×8=88 8×(8-(8÷8)÷8)=88 8×(8-((8÷8)÷8))=88 8×(8-(8÷8)÷8)=88 8×(8-((8÷8)÷8))=88 (8-(8÷8)÷8)×

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