If the point P (2, 1) lies on the line segment joining points A (4, 2) and B (8, 4), then

Given,

Point P (2, 1) lies on the line segment AB, joining the points A (4, 2) and B (8, 4);



Now,


The distance between A (4, 2) and P (2, 1),


By using the distance formula;


Distance between two points (x1, y1) and (x2, y2),


d =


AP =




Distance between A (4, 2) and B (8, 4)


AB




Distance between B (8, 4) and P (2, 1),


BP =





AB =


2AP = AB



Hence, required condition is AP =

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