Find the coordinates of the point which divides the line segment joining the points

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

and

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

in the ratio (i)

    \[\mathbf{2}:\text{ }\mathbf{3}\]

internally, (ii)

    \[\mathbf{2}:\text{ }\mathbf{3}\]

externally.
Find the coordinates of the point which divides the line segment joining the points

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

and

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

in the ratio (i)

    \[\mathbf{2}:\text{ }\mathbf{3}\]

internally, (ii)

    \[\mathbf{2}:\text{ }\mathbf{3}\]

externally.

Solution:

Let the line segment joining the points A

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

and B

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

be AB.

(i) 

    \[\mathbf{2}:\text{ }\mathbf{3}\]

internally

By using section formula,

So, the coordinates of the point which divides the line segment joining the points A

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

and B

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

in the ratio

    \[\mathbf{2}:\text{ }\mathbf{3}\]

internally is given by:

Hence, the coordinates of the point which divides the line segment joining the points

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

and

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

is

    \[\left( -4/5,\text{ }1/5,\text{ }27/5 \right)\]

(ii)

    \[\mathbf{2}:\text{ }\mathbf{3}\]

externally

By using section formula,

So, the coordinates of the point which divides the line segment joining the points A

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

 B

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

in the ratio

    \[\mathbf{2}:\text{ }\mathbf{3}\]

externally is given by:

∴ The co-ordinates of the point which divides the line segment joining the points

    \[\left( \text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{5} \right)\]

) and

    \[\left( \mathbf{1},\text{ }\text{ }\mathbf{4},\text{ }\mathbf{6} \right)\]

is

    \[\left( -8,\text{ }17,\text{ }3 \right)\]