标签：des c class a int width
The Circumference of the
Circle
| Time Limit: 1000MS |
|
Memory Limit: 65536K |
| Total Submissions: 7032 |
|
Accepted: 4361 |
Description
To calculate the circumference of a circle seems
to be an easy task - provided you know its diameter. But what if you
don‘t?
You are given the cartesian coordinates of three
non-collinear points in the plane.
Your job is to calculate the
circumference of the unique circle that intersects all three points.
Input
The input will contain one or more test cases.
Each test case consists of one line containing six real numbers x1,y1,
x2,y2,x3,y3, representing the coordinates of the three points. The diameter of
the circle determined by the three points will never exceed a million. Input is
terminated by end of file.
Output
For each test case, print one line containing one
real number telling the circumference of the circle determined by the three
points. The circumference is to be printed accurately rounded to two decimals.
The value of pi is approximately 3.141592653589793.
Sample Input
0.0 -0.5 0.5 0.0 0.0 0.5
0.0 0.0 0.0 1.0 1.0 1.0
5.0 5.0 5.0 7.0 4.0 6.0
0.0 0.0 -1.0 7.0 7.0 7.0
50.0 50.0 50.0 70.0 40.0 60.0
0.0 0.0 10.0 0.0 20.0 1.0
0.0 -500000.0 500000.0 0.0 0.0 500000.0
Sample Output
3.14
4.44
6.28
31.42
62.83
632.24
3141592.65
Source
Ulm Local 1996
主要用到海伦公式，正弦定理。没什么难度，当然也可以用行列式。原理就是平面几何里面的垂直的左边乘积等于-1，然后建立等式。
poj2242,布布扣,bubuko.com
poj2242
标签：des c class a int width
原文地址：http://www.cnblogs.com/jhldreams/p/3753826.html
