# Скачать Calculating a Circle by 3 Points Coordinates

16.12.1992
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This program does not give the proper answer or I may be feeding it improper coordinates. I need someone to tell me, "Yes, this is the proper formula" or, "No, there is a mistake here!" or, "Here is the right way to get the answer". I would like to know if there is any one who can tell me what book this came out of. I copied this formula from a book about two years ago but all I know is that it was on page 63. I can't remember the title of the book. If you know where I can find this formula or have a similar one... please let me know.

There are some conditions that I'm sure must be meet. 1st of all, all 3 X and Y coordinates MUST BE ON A CIRCLE. It is possible to have 3 points that can not be on a circle!

If ya find out anything...please leave me mail on this BBS or EXEC -PC or CHANNEL1 or PIER1 in Buffalo, NY or call my BBS.

Here is the formula!

Circle passing through 3 given points

```Let  ( X1, Y1 ) = M1, ( X2, Y2 ) = M2, ( X3, Y3 ) =M3

1) The slope of the straight line joining M1 and M2 is;

Y2 - Y1
-------
X2 - X1

2) The slope of the perpendicular to this line is;

X2 - X1
- -------
Y2 - Y1

3) The equation of the bisector of the segment M1,M2 is;

Y1 + Y2   X2 - X1        X1 + X2
Y = ------- - -------- ( X - ------- )
2      Y2 - Y1           2

4) Similarly, the equation of the bisector of the segment
M1,M3 is;

Y1 + Y2   X3 - X1        X1 + X3
Y = ------- - -------  ( X - ------- )
2      Y3 - Y1           2

5) These 2 equations can be written in the form;

Y = K2X + H2
Y = K3X + H3

X2 - X1           X3 - X1
where;  K2 = - -------    K3 = - ------- and
Y2 - Y1
```