This applet lets you explore congruent angles formed by parallel lines with transformations.

1) Are the lines parallel? How do you know?[br]2) Drag points B and C to show that lines remain parallel.[br]3) Click “Step 1.” What transformation maps <HBD onto <H’BD’? [br] a) 180o Rotation b) Reflection c) Translation[br]4) Click “Step 2.” What transformation maps <D’BH’ onto <D”CH”?[br]a) 180o Rotation b) Reflection c) Translation[br]5) Click “Step 3.” What transformation maps <D”CH” onto <D’’’CH’’’?[br]6) a) 180o Rotation b) Reflection c) Translation[br]7) Drag points B and C to show that angles remain congruent. Drag points D and H to show that the transformations maintain congruence.[br]EXAMPLE: Write a paragraph proof. Prove that <1 is congruent to <3 using transformations.[br]A 180o Rotation maps <1 onto <2 therefore <1 <2. A translation maps <2 onto <3 therefore <2 <3. By transitive property <1 s congruent to <3.[br]8) Write a paragraph proof, using transformations, proving <2 s congruent to <4.