Theory:

median of a triangle is a line segment joining a vertex to the midpoint of the opposite side.
Let us construct a median of a triangle.

Consider a triangle $$ABC$$,

To draw the median, we need to consider the desired vertex (suppose $$A$$) and its opposite side ($$BC$$).

The midpoint of the side $$BC$$ can be found by first constructing the perpendicular bisector (with the help of compass) on $$BC$$ and joining the intersecting arcs.

Let $$D$$ be the mid-point of $$BC$$.

Now join the point $$D$$ and the opposite vertex $$A$$.  This line segment $$AD$$ is the median of a triangle $$ABC$$.

Important!
• As there are three vertices for any triangle, every triangle has three medians, one from each vertex. That is, every triangle has exactly three medians.
• Thus, a median connects a vertex of a triangle to the mid-point of the opposite side.