Find the equations of the medians of a triangle, the equations of whose sides are: 3x + 2y + 6 = 0, 2x – 5y + 4 = 0 and x – 3y – 6 = 0
Find the equations of the medians of a triangle, the equations of whose sides are: 3x + 2y + 6 = 0, 2x – 5y + 4 = 0 and x – 3y – 6 = 0

Given:

    \[3x\text{ }+\text{ }2y\text{ }+\text{ }6\text{ }=\text{ }0\text{ }\ldots \text{ }\left( 1 \right)\]

    \[2x\text{ }-\text{ }5y\text{ }+\text{ }4\text{ }=\text{ }0\text{ }\ldots \text{ }\left( 2 \right)\]

And

    \[x\text{ }-\text{ }3y\text{ }-\text{ }6\text{ }=\text{ }0\text{ }\ldots \text{ }\left( 3 \right)\]

Let us assume, in triangle ABC, let equations (1), (2) and (3) represent the sides AB, BC and CA, respectively.

Solving equations (1) and (2), we have

    \[x\text{ }=\text{ }-2,\]

    \[~y\text{ }=\text{ }0\]

Thus, AB and BC intersect at

    \[B\text{ }\left( -2,\text{ }0 \right).\]

Now, solving (1) and (3), we have

    \[x\text{ }=\text{ }\text{ }6/11,\text{ }y\text{ }=\text{ }\text{ }24/11\]

Thus, AB and CA intersect at

    \[A\text{ }\left( -6/11,\text{ }-24/11 \right)\]

Similarly, solving (2) and (3), we get

    \[x\text{ }=\text{ }-42,\text{ }y\text{ }=\text{ }-16\]

Thus, BC and CA intersect at

    \[C\text{ }\left( -42,\text{ }-16 \right).\]

Now,

let D, E and F be the midpoints the sides

BC, CA and AB, respectively.

Then, we have:

RD Sharma Solutions for Class 11 Maths Chapter 23 – The Straight Lines - image 56

RD Sharma Solutions for Class 11 Maths Chapter 23 – The Straight Lines - image 57

∴ The equations of the medians of a triangle are:

    \[41x\text{ }\text{ }112y\text{ }\text{ }70\text{ }=\text{ }0,\]

    \[16x\text{ }\text{ }59y\text{ }\text{ }120\text{ }=\text{ }0,\]

And,

    \[25x\text{ }\text{ }53y\text{ }+\text{ }50\text{ }=\text{ }0\]