Midsegment of a Triangle
A line segment joining the midpoints of two sides of a triangle.
A triangle has 3 possible midsegments.
Try this Drag the orange dots on each vertex to reshape the triangle. Notice the behavior of the midsegment line.

Properties

  1. The midsegment is always parallel to the third side of the triangle. In the figure above, drag any point around and convince yourself that this is always true.
  2. The midsegment is always half the length of the third side. In the figure above, drag point A around. Notice the midsegment length never changes because the side BC never changes.
  3. A triangle has three possible midsegments, depending on which pair of sides is initially joined.

Related triangle topics

General

Perimeter / Area

Triangle types

Triangle centers

Congruence and Similarity

Solving triangles

Triangle quizzes and exercises

COMMON CORE

Math Open Reference now has a Common Core alignment.

See which resources are available on this site for each element of the Common Core standards.

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