8.9Midsegments of Triangles and Trapezoids
Quick Answer
Triangle Midsegment Theorem: the segment connecting the midpoints of two sides is parallel to the third side and half its length. Trapezoid Midsegment Theorem: the midsegment is parallel to the bases and its length equals the average of the bases.
Essential Question
How do the triangle and trapezoid midsegment theorems both express the same idea — that a midsegment is parallel to and half the length of the base — in different contexts?
Learning Goals
- 1State and apply the Triangle Midsegment Theorem.
- 2State and apply the Trapezoid Midsegment Theorem.
- 3Find midsegment lengths using the theorems.
- 4Prove midsegment theorems using coordinates.
Key Vocabulary
Midsegment (triangle)
The segment connecting the midpoints of two sides; parallel to the third side and half its length.
Midsegment (trapezoid)
The segment connecting the midpoints of the legs; parallel to the bases and equal to their average.
Full lesson content coming soon
Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.