If the equation of a circle is x ^ 2 y ^ 2-4y = 0, then the coordinate of the center of the circle is? What is the radius r? How to substitute it into the formula,

If the equation of a circle is x ^ 2 y ^ 2-4y = 0, then the coordinate of the center of the circle is? What is the radius r? How to substitute it into the formula,

x^2 +y^2-4y=0
x²+(y-2)²=4
x²+(y-2)²=2²
Then the center coordinates of the circle are (0,2)
The radius R is two

The more detailed the formulas, the better. It's best to have a description
Some of the previous formulas are also given

The standard equation of a circle is (x-a) 2 + (y-b) 2 = R2, and the center of the circle is (a, b). If the center of the circle is at the standard origin, this is a = 0, B = 0, then the equation of the circle is x2 + Y2 = R2 (x-a) 2 + (y-b) 2 = R2. Note: (a, b) is the general equation of the center coordinate circle, which is expanded from (x-a) 2 + (y-b) 2 = R2 to x2 + y2-2ax-2by + A2 + b2-r

English questions (about phrase translation and words)
Please write down the simple three forms, present participle and past tense of the following verbs
prefer_____ _____ _____ believe_____ _____ ______
agree_____ _____ _____ speak_____ _____ ______
sit_____ _____ _____ die___ _____ _____
ask_____ _____ _____ read_____ _____ _____
Phrase translation: convenient time___________ Many vehicles__________

prefer - prefers - preferring - preferred; believe - believes - believing - believed;
agree - agrees - agreeing - agreed; speak - speaks - speaking - spoke;
sit - sits - sitting - sat; die - dies - dying - died;
ask - asks - asking - asked; read - reads -reading -read.
At your convenience; when it is convenient for you;
Many vehicles, a lot of cars, a lot of traffic

The sum of the numerator and denominator of a fraction is 29. If the numerator and denominator are reduced by 2 and simplified to 23, what is the original fraction?

Some and any modify countable nouns or uncountable nouns

Some and any can modify both countable and uncountable nouns

If 3 / A + 2 = 4 / b = 6 / C + 5, and 2a-b + 3C = 21
It's urgent!

A + 2 / 3 = B / 4 = C + 5 / 6, 4A + 8 = 3b, 2C + 10 = 3b, 2A = C + 1, combined with 2a-b + 3C = 21
A = 4, B = 8, C = 7, so a: B: C = 4:8:7

Let's analyze the composition of this sentence
It is difficult to the point of impossibility for the average reader under the age of forty to image a time when high-quality arts criticism could be found in most big-city newspapers.
What I don't know is what the prepositional phrase for is, whether it is an attributive or an object complement, and the prepositional phrase to in front of it

It is difficult to image a time
The prepositional phrase for acts as an adverbial; the prepositional phrase to before it also acts as an adverbial

BD and CE are the height of triangle ABC, G and F are the midpoint of BC and de respectively. It is suggested that FG is perpendicular to de

Connect eg and DG
Then eg = DG = BC / 2 (center line of right triangle hypotenuse = half of hypotenuse)
And because f is the midpoint of ED
Then FG vertical ed (three wires in one)

Plural of dish

It ends with X, s, SH, CH, a few with O and es
As for the few words that end in O, there are only four words:
Negro: Negro
Hero: Hero
Tomato: Tomato
Potato
You can remember this: Black heroes love potatoes and tomatoes
So it should be dishes

In △ ABC, if Sina = 2sinb, AC = 2, then BC=______ ．

From the sine theorem, we can know that acsinb = bcsina  BC = acsinb · Sina = 2 × 2 = 4, so the answer is: 4