Let A (2, 2, – 3), B (5, 6, 9) and C (2, 7, 9) be the vertices of a triangle. The internal bisector of the angle A meets BC at the point D. Find the coordinates of D.
Let us assume that the coordinates of D are (x,y,z).
Now,
AB =
= = 13
AC =
= = 13
Thus, AB = AC.
Thus, ABC is an isosceles triangle.
Now, D is the mid-point of BC or Angle bisector AD bisects BD,
Thus, D = (5+2/2, 6+7/2, 9+9/2)
= (7/2, 13/2,9)