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GeoGebraGeoGebra Classroom

Midsegments in a Quadrilateral

Sketch a Quadrilateral using the Polygon Tool.

  1. Construct the midpoints of each side of the quadrilateral. Toolbar Image
  2. Connect the midpoints of each pair of consecutive sides.Toolbar Image
Describe the shape created by connecting the midpoints.

Sketch a DIFFERENT Quadrilateral using the Polygon Tool.

  1. Construct the midpoints of each side of the quadrilateral. Toolbar Image
  2. Connect the midpoints of each pair of consecutive sides.Toolbar Image
Describe the shape created by connecting the midpoints.

Justify your answer to Task 4 ? (You may need to use some measurement tools to verify your answer.)

Construct the midpoints of two sides of this Triangle:

  • Connect the midpoints Toolbar Image of two consecutive sides.Toolbar Image This is a MIDSEGMENT of the triangle.
How does the length of the midsegment compare to the length of the 3rd side?

  • Compare the slopes of the midsegment and the 3rd side. Toolbar Image
What does the slope measurements tell you about these two segments ?

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    How do your answers to Task 7 and Task 8 agree with the Triangle Midsegment Theorem ?

    Construct Triangle BCD using the Polygon Tool.

    • Connect the midpoints (red points) of sides CD and BD using the segment tool Toolbar Image
    • Connect the midpoints (red points) of sides AB and AC using the segment tool Toolbar Image
    What does the slope measurements tell you about these two midsegments ?

    Compare the lengths of the two midsegments:

    Theorem 6-15

    Theorem 6-15

    • Connect the midpoints of the sides of Quadrilateral ABCD using the Polygon Tool. Toolbar Image
    What does Theorem 6-15 claim about the quadrilateral that connects the midpoints of the sides of Quadrilateral ABCD ?

    Yippee! Congrats on finishing this Activity.