Diagonals to Quadrilaterals II

  • Diagonals to Quadrilaterals II

    Grade: High School

    What types of quadrilaterals are formed when various restrictions are placed on the diagonals?

    Activity

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    Instructions

    The Show and Hide buttons allow three different quadrilaterals and their measurements to appear or disappear on the screen, with the following properties:

    • Show/Hide Perpendicular Bisectors: Draws a quadrilateral for which the diagonals bisect one another and meet at a right angle.
    • Show/Hide Perpendicular Bisectors Congruent: Same as above, but the diagonals are also equal in length.
    • Show/Hide Congruent Bisectors: The diagonals have equal length and bisect one another.

     

    Exploration

    Click Show Perpendicular Bisectors. Notice that the measurements of the four interior segments are displayed.

    • Given the measurements of the half-diagonals, what can you conclude about the side lengths of the quadrilateral that is formed?
    • Drag any of the red points to change the size and shape of the quadrilateral. Does the relationship between the side lengths change?
    • What types of quadrilaterals can be formed if the diagonals are perpendicular bisectors?

    Conduct a similar investigation for Perpendicular Bisectors Congruent and for Congruent Bisectors. What types of quadrilaterals are formed in each of these cases?

     

    Objectives and Standards

    NCTM Standards and Expectations
    • Geometry / Measurement
    • Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.
    • High School (9-12)
    • Geometry