Circular Area 两圆相交面积（模板）

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Circular Area

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 5272 Accepted: 2100

Description

Your task is to write a program, which, given two circles, calculates the area of their intersection with the accuracy of three digits after decimal point.

Input

In the single line of input file there are space-separated real numbers x1 y1 r1 x2 y2 r2. They represent center coordinates and radii of two circles.

Output

The output file must contain single real number - the area.

Sample Input

20.0 30.0 15.0 40.0 30.0 30.0

Sample Output

608.366

套模板求解两圆相交的面积

code：

<span style="font-size:18px;">#include<iostream>#include<stdio.h>#include<cmath>#include<cstring>using namespace std;const double pi = 3.141592653;int flag;double solve( double r, double r0, double dis ){  double ang = 2*acos( (r*r + dis*dis - r0*r0) / (2*r*dis ) );//公式  double s2  = 0.5*r*r*sin(ang);  double s1  = 0.5*r*r*ang;  return s1 - s2;}int main( ){  double x,y,r,x0,y0,r0,dis,ans;//freopen("input.txt","r",stdin);//freopen("output.txt","w",stdout);  while( scanf( "%lf%lf%lf%lf%lf%lf",&x,&y,&r,&x0,&y0,&r0 ) != EOF )  {    flag=0;    dis = sqrt( ( x - x0 )*( x - x0 ) + ( y - y0 )*( y - y0 ) );    if( r < r0 )    swap(r,r0);    if(dis>=(r+r0))        printf("0.000\n");    else if(dis+r0<=r)        printf("%.3lf\n",pi*r0*r0);    else        printf("%.3lf\n",solve(r,r0,dis)+solve(r0,r,dis));  }  return 0;}</span>

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