Name ______Date ______

Lab: Exploring Midsegments of Trapezoids with Geometer’s Sketchpad

Objective: To investigate the properties of midsegments

Investigation

  1. Using the point button (2nd button down), construct two points.
    Using the text button (5th button down), label your points A and B.
    Then, highlight both points A and B and select the menu options “Construct  Line”.

  1. Construct a new point below line AB.
    Using the text button, label your new pointC.
    Then highlight point C and line AB, and select the menu options “Construct  Parallel Line”.
    After the line appears, construct a fourth pointto the left of Cusing the point button.
    Last, using the label button, label your new point as pointD

  1. Select the “Line Segment” tool (4th button down) and construct segments AD and BC.
  1. Highlight both and use the menu options “Construct  Midpoints”
    Note: keyboard shortcut is Ctrl+M on a PC or Command+M on a Mac.
    Using the text button, label them X and Y
    Note: After the labels show up, you might need to change the letters. To do so,
    double click on the letter that appeared and type in the new letter.
    Then construct the segment XY.
  1. Highlight in your diagram.
    Then use the menu option “Measure  Lengths”.
    Record your results in the spaces below.

AB = ______DC = ______XY = ______AB + DC = ______

  1. Move the points, segments, etc. of trapezoid ABCD around 3 more times. Write your results in the space below.

AB = ______DC = ______XY = ______AB + DC = ______
AB = ______DC = ______XY = ______AB + DC = ______

AB = ______DC = ______XY = ______AB + DC = ______

How does the midsegment relate to the two bases?

  1. Write a conjecture about the midsegment of a trapezoid.

Geometry – Quadrilaterals -1- NJCTL.org