poj 2986 A Triangle and a Circle

[mtttt]

A Triangle and a Circle
Time Limit: 5000MS Memory Limit: 131072K
Total Submissions: 1194 Accepted: 214 Special Judge

Description

Given one triangle and one circle in the plane. Your task is to calculate the common area of these two figures.

Input

The input will contain several test cases. Each line of input describes a test case. Each test case consists of nine floating point numbers, x1, y1, x2, y2, x3, y3, x4, y4 and r, where (x1, y1), (x2, y2) and (x3, y3) are the three vertices of the triangle and (x4, y4) is the center of the circle and r is the radius. We guarantee the triangle and the circle are not degenerate.

Output

For each test case you should output one real number, which is the common area of the triangle and the circle, on a separate line. The result should be rounded to two decimal places.

Sample Input

0 20 10 0 -10 0 0 0 10
Sample Output

144.35
Source

POJ Monthly--2006.08.27, Rainer

哪位大侠提供点思路呗，不甚感激