The point dividing ABABAB internally in ratio m:nm:nm:n has coordinates P=(mx2+nx1m+n,my2+ny1m+n)P = \left(\dfrac{mx_2 + nx_1}{m+n}, \dfrac{my_2 + ny_1}{m+n}\right)P=(m+nmx2+nx1,m+nmy2+ny1). For external division, replace nnn by −n-n−n. Midpoint is m:n=1:1m:n = 1:1m:n=1:1.