IGD Dropping a Perpendicular Line

  • IGD: Dropping a Perpendicular Line

    Grade: High School

    Constructing a line perpendicular to a given line and through a point not on the line is one of the most important constructions in geometry. This process is known as dropping a perpendicular, because a perpendicular line is "dropped" from the point to the line.



        How to Use


        ·  Use the points on the sliders to adjust the radii of the circles.

        ·  You can drag points to change the location and orientation of the construction.




        The buttons will appear sequentially.

        The Reset button will allow you to start over.



    • Construct a proof of this construction. If you need a hint, click on the Hint- Why It Works button at the end of the construction.
    •  Where do you see perpendicular lines in real-life.
    •  Create a scenario where you would need to drop a perpendicular line from a specific point.

    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