%求兩個(gè)圓(圓心為x1,y1半徑為r1和圓心為x2,y2半徑為r2)的兩個(gè)交點(diǎn)(rp1x,rp1y)和(rp2x,rp2y)
%利用余弦定理
function [rp1x,rp1y,rp2x,rp2y]=c2point(x1,y1,r1,x2,y2,r2) 
    a=x2-x1; 
    b=y2-y1; 
    r=(a*a+b*b+r1*r1-r2*r2)/2; 
    if(a==0)&&(b~=0)
        rp1y=r/b;
        rp2y=r/b; 
        rp1x=sqrt(r1*r1-rp1y*rp1y); 
        rp2x=-rp1x; 
    end
    if(a~=0&&b==0)  
        rp1x=r/a; 
        rp2x=r/a; 
        rp1y=sqrt(r1*r1-rp1x*rp2x); 
        rp2y=-rp1y; 
    end
    if(a~=0&&b~=0)  
        delta=b*b*r*r-(a*a+b*b)*(r*r-r1*r1*a*a); 
        rp1y=(b*r+sqrt(delta))/(a*a+b*b); 
        rp2y=(b*r-sqrt(delta))/(a*a+b*b); 
        rp1x=(r-b*rp1y)/a; 
        rp2x=(r-b*rp2y)/a; 
    end
    rp1x=x1+rp1x; 
    rp1y=y1+rp1y; 
    rp2x=x1+rp2x; 
    rp2y=y1+rp2y; 

%ezplot('(x-x1)^2+(y-y1)^2-r1^2');    %繪制隱函數(shù)曲線(xiàn)  
%hold on;
%ezplot('(x-x2)^2+(y-y2)^2-r2^2');
%調(diào)用函數(shù)c2point
%[rp1x,rp1y,rp2x,rp2y]=c2point(x1,y1,r1,x2,y2,r2);
%繪制交點(diǎn)
%plot(rp1x,rp1y,'*g');
%plot(rp2x,rp2y,'*g');
%hold off