Q: A(2,3), B(8,9) have position vectors a, b. Find the position vector of P dividing AB internally 2:1, and the midpoint M. p = (2b+1a)/3 = (2(8,9)+(2,3))/3 = ((16+2)/3, (18+3)/3) = (6,7). Midpoint: (a+b)/2 = (5,6).