Shape 

Copyright David & Cynthia Thomas, 2009

 

Transformation Geometry--Directed Activity: Reflection

                                                                               

Focus

Reflection using coordinate geometry. 

Technologies

5 mm grid paper, The Geometers Sketchpad and the model 5_Reflections.gsp

Background

Figure 5.23 shows ΔABC and three mirrors corresponding to three reflections, m, n, and o.

Figure 5.23: Reflections

Tasks

·        Using coordinate geometry and 5 mm grid paper, find the image of ΔABC (i.e., give the coordinates of the vertices) under reflection

  • m
  • n
  • o
  • The composition of all three reflections

§         First m, then n, then o

§         First n, then m, then o

§         First o, then m, then n

  • How does varying the order of reflections affect the final result?

·        Check your findings using The Geometers Sketchpad, and the model 5_Reflections.gsp