IM 8.1.16 Lesson: Parallel Lines and the Angle in a Triangle

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• Offline Activity (.zip)

• GeoGebra Files

  1. Consider triangle ABC. Select the Midpoint tool and click on two points or a segment to find the midpoint. (.ggb)
     
  2. Here is triangle △ABC. Line DE is parallel to line AC. (.ggb)
     
  3. Create a few quadrilaterals. Use a protractor to measure the four angles inside the quadrilateral. What is the sum of these four angle measures? (.ggb)
     
  4. This diagram shows a square BDFH that has been made by images of triangle ABC under rigid transformations. Given that angle BAC measures 53 degrees, find as many other angle measures as you c (.ggb)