Skill: Determine the midpoint of a line segment

Explanation and Free Practice Resources

The midpoint of a line segment in the Cartesian plane is the point halfway between its endpoints, with equal distance to each endpoint; its coordinates are found by averaging the corresponding xx-coordinates and the corresponding yy-coordinates, M(x1+x22,y1+y22)M\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right), including results that may be fractions or decimals. This understanding supports coordinate proofs, distance relationships, and geometric transformations; the scope is limited to two-dimensional Cartesian coordinates, not three-dimensional or more abstract vector generalizations.

Detailed Explanation: Determine the midpoint of a line segment

The midpoint is the point exactly halfway between the two endpoints of a line segment. To find it, average the two xx-coordinates and average the two yy-coordinates:

M(x1+x22,y1+y22)M\left(\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\right)

Example

Find the midpoint of the segment with endpoints A(−3,5)A(-3,5) and B(7,−1)B(7,-1).

Step 1: Identify the coordinates.

x1=−3,y1=5,x2=7,y2=−1x_1=-3,\quad y_1=5,\quad x_2=7,\quad y_2=-1

Step 2: Average the xx-coordinates.

x1+x22=−3+72=42=2\frac{x_1+x_2}{2} =\frac{-3+7}{2} =\frac{4}{2} =2

Step 3: Average the yy-coordinates.

y1+y22=5+(−1)2=42=2\frac{y_1+y_2}{2} =\frac{5+(-1)}{2} =\frac{4}{2} =2

Step 4: Write the midpoint.

M(2,2)\boxed{M(2,2)}

So, the midpoint of the segment from (−3,5)(-3,5) to (7,−1)(7,-1) is (2,2)(2,2). Always average corresponding coordinates: the xx-coordinates together and the yy-coordinates together.

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Line Segment (Points) - Find Midpoint (Coordinate)


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