Find the coordinates of the points of trisection of the line segment joining (4, –1) and (–2, –3).

Let P and Q be the point of trisection of AB. Then,
AP = PQ = QB = 1
Case I. Here P divides AB in the ratio 1 : 2.
So, we have
x1 = 4, y1 = -1
x2 = -2, y2 = -3
and m1 = 1, m2 = 2
∴ The coordinates of P are given by
Case II. Here, Q divides AB in the ratio 2 : 1. So, we have
x1 = 4, y1 = -1
x2 = 2, y2 = -3
and m1 = 2, m2 = 1
∴ The coordinates of Q are given by