The distance formula is an algebraic expression used to determine the distance between two points with the coordinates (x1, y1) and (x2, y2).
D=(x2−x1)2+(y2−y1)2−−−−−−−−−−−−−−−−−−√D=(x2−x1)2+(y2−y1)2ExampleFind the distance between (-1, 1) and (3, 4).This problem is solved simply by plugging our x- and y-values into the distance formula:D=(3−(−1))2+(4−1)2−−−−−−−−−−−−−−−−−−√=D=(3−(−1))2+(4−1)2==16+9−−−−−√=25−−√=5=16+9=25=5Sometimes you need to find the point that is exactly between two other points. This middle point is called the "midpoint". By definition, a midpoint of a line segment is the point on that line segment that divides the segment in two congruent segments.If the end points of a line segment is (x1, y1) and (x2, y2) then the midpoint of the line segment has the coordinates:(x1+x22,y1+y22)(x1+x22,y1+y22)