Sketchpad - Sum of the Angles of a Euclidean Triangle





Straight Edge      


Script View      

Sketchpad Exploration

  • Choose the Straight Edge Tool. Create a triangle by clicking down somewhere, releasing, moving somewhere else, clicking down again, and repeating until you have a triangle.
  • Choose the Arrowhead Tool and hold down the shift key in order to choose three vertices. The order you choose your vertices will designate a specific angle of your triangle. Under Measure release on Angle. Notice that Sketchpad will measure the angle that you chose and will label it for you.
  • Repeat to measure the other two angles in your triangle.
  • Remember to click on the white background in between measurements in order to ensure that nothing is selected.
  • Under Measure release on Calculate... Click on the first angle measurement and then on plus. Then click on the second angle measurement and then on plus. Finally, click on the third angle measurement and then on OK.
  • Drag your triangle around to see what happens to the angle measurement.