Who can teach me how to calculate this mathematical formula? The problem is as follows: (I can't draw a picture, only by saying) there is a straight line from point a to point B. We know that its length is a, and there is a point C between two points AB, AC = BC, AC + BC = AB or A. at this time, draw a line perpendicular to ab from point C to point D, and we know that the length of CD is B, which is not equal to a, How long is the length of this arc? (for example: a = 20 meters, B = 2 meters) how to calculate, and what is its formula? I hope which expert can give an accurate formula! I'm sorry, R & sup2; = (A / 2) & sup2; + (R-B) & sup2; why r = (A & sup2; + 4B & sup2;) / 8b, how to check its formula? In addition, can you explain how to work out the formula of ∠ AOD degree again? Trouble my friend!

Who can teach me how to calculate this mathematical formula? The problem is as follows: (I can't draw a picture, only by saying) there is a straight line from point a to point B. We know that its length is a, and there is a point C between two points AB, AC = BC, AC + BC = AB or A. at this time, draw a line perpendicular to ab from point C to point D, and we know that the length of CD is B, which is not equal to a, How long is the length of this arc? (for example: a = 20 meters, B = 2 meters) how to calculate, and what is its formula? I hope which expert can give an accurate formula! I'm sorry, R & sup2; = (A / 2) & sup2; + (R-B) & sup2; why r = (A & sup2; + 4B & sup2;) / 8b, how to check its formula? In addition, can you explain how to work out the formula of ∠ AOD degree again? Trouble my friend!

Let AB = a, CD = B, the center of the arc is O, the radius is r, the key is to find out the degree of the center angle
Then in RT △ AOC, by Pythagorean theorem,
OA & sup2; = AC & sup2; + OC & sup2;, namely R & sup2; = (A / 2) & sup2; + (R-B) & sup2;,
R = (A & sup2; + 4B & sup2;) / 8b,
Then sin ∠ AOD = AC / OA = 4AB / (A & sup2; + 4B & sup2;),
Find out the degree of ∠ AOD, and set it as n,
Then the length of arc ad is L = n π R / 180,
The length of arc ADB is 2L = 2n π R / 180 = n π R / 90
If a = 20m, B = 2m, then r = 26,
sin∠AOD=0.3846,sin∠AOD=22.62°,
The length of arc ADB is n π R / 90
=22.62 * 3.14 * 26 / 90 = 20.52 (m)

According to the law of the first three numbers, write the next number. 234534523

5234

Priority mathematics of set sign
Odd numbers belong to both integers (z) and rational numbers (q). Do they exist in two sets at the same time?
Do set symbols have precedence? Or habit order?

In general, odd numbers are attributed to integer sets, odd numbers to integers, and integers to rational numbers

Correct pronunciation of English words
They are written in our Chinese characters
That's it. I'm not sure about the pronunciation of this word

This tongue biter can't read it in Chinese ~ you bite a little bit of tongue, like pronouncing pinyin "Z", and then pronounce "Er". Remember to bite your tongue~

Given that the circle x ^ 2 + y ^ 2 + x-6y + M = 0 intersects the line x + 2y-3 = 0 and PQ, O is the origin, and op ⊥ OQ, find M
For specific data

By substituting a straight line into a circular equation, we can solve the coordinates of P and Q, which contain M. then we can solve m by using OP ⊥ OQ, that is, the vector opxoq = 0

For a project, it is planned to pave 3.2km per day. In fact, it is 25% more than the plan per day. In fact, it will be completed in 12 days. How many days is it planned to be completed?
Using equation

The plan will be finished in X days
3.2*（1+25%）*12=3.2X
3.2*5/4*12=3.2X
3.2X=48
X=15
A: it is planned to finish in 15 days

Solve the equation log2 (x ^ 2-3) = 2log4 (6x-10) - 1

log2(x^2-3)=log4(6x-10)^2-log4(4)
x^2-3=(6x-10)^2/4
4x^2-12=36x^2-120x+100
4x^2-15x+14=0
(4x-7)(x-2)=0
x1=7/4,x2=2

If F1 and F2 are the two focal points of the ellipse X225 + Y29 = 1, make a straight line through F1 and intersect the ellipse at two points a and B, the perimeter of △ abf2 is______ ．

From the ellipse X225 + Y29 = 1, a = 5, B = 3, the circumference of △ abf2 is (& nbsp; AF1 + af2 & nbsp;) + (BF1 + BF2) = 2A + 2A = 4A = 20, so the answer is: 20

How to write bread in English?
Clean your Room
Bob' mom is mad.
His room is a mess!
She says,"Clean your room!"
Bob puts his toys under his bed.
Bob puts his dirty clothes under his bed.
Bob puts his books under his bed.
He says,"My room is clean now."
(1) Choose the right answer
What's Bob doing?
A.Cleaning a room.B.Making a mess.
C.shopping for toys.D.Sleeping in a bed.

Clean your room mad.Bob She says, "clean your room!" she says, "clean your room!" Bob puts his toys under his bed.Bob ...

If the polynomial 2x ^ m - (n + 2) x-3 is a quadratic binomial about X, find the values of M and n

Because the polynomial 2x ^ m - (n + 2) x-3 is a quadratic binomial of X
So m = 2 and N + 2 = 0,
So m = 2, n = - 2