In geometrical figure problems we draw many line segments to break the figure to get results easily. For example, to find the perimeter of a semicircle, divide the circle by drawing a line segment passing through its center called diameter. Similarly when a line joining two midpoints of two sides of a triangle is called mid-segment. Usually composite figures are best analyzed by dividing them into smaller figures. In this section will study about definition, properties and some theorems on triangle mid-segment.