已知三角形ABC,三顶点坐标为A[x1,y1],B[x2,y2],C[x3,y3],三边为a,b,c面积为S[ABC],那么 |x1 y1 1| |x2 y2 1|=2*S[ABC] |x3 y3 1| a=sqrt((x1-x2)^2+(y1-y2)^2) b=sqrt((x2-x3)^2+(y2-y3)^2) c=sqrt((x1-x3)^2+(y1-y3...