设三角形三点分别为(x1,y1),(x2,y2),(x3,y3)则一条边长为 :根号下(x2-x1)^2+(y2-y1)^2另两边中点为((x1+x3)/2,(y1+y3)/2),和((x2+x3)/2,(y2+y3)/2)这两中点距离为:根号下((x2+x3)/2-(x1+x3)/2)^2+((y2+y3)/2-(y1+y3)...