in the diagram, c and d are located such that ab is divided into three equal parts. what are the coordinates of c and d?

Step-by-step

Topic: Points of division

There are scary looking formulas that can be used, but it is much easier to calculate by reasoning.

Given : A(-3,6), B(6,-3)

Solution:

The idea is to subdivide the DIFFERENCE in coordinates into thirds, and add onto that of A.  We choose A as the starting point, but method works equally well if we chose B.

Difference in coordinates (delta) between A & B is then

delta(Bx-Ax, By-Ay)

=(6-(-3), -3-6)

=delta(9, -9)

One third of difference (for point C)

=delta/3 = (3,-3)

So coordinates of point C

= A(-3,6)+(3,-3)

= C(0,3)

Two thirds of difference (for point D)

= (2/3)delta = (6, -6)

Coordinates for point D

= A(-3,6)+(6,-6)

= D(3,0)

If you prefer to use formulas, it would be

New coordinates = (Xa+(Xb-Xa)*k, Ya+(Yb-Ya)*k)

where

Xa,Xb = x-coordinates of points A & B respectively.

Ya,Yb = y-coordinates of points A & B respectively.

k=ratio (usually less than 1)

Here

k for point C = 1/3

k for point D = 2/3