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Session 5: Notes
 
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Notes for Session 5, Part C


Note 4

If you are working in a group, check to see if anyone used a cutting method similar to the one presented here. If so, consider using their method to launch the proof rather than the one shown here.

<< back to Part C: The Midline Theorem


 

Note 5

Spend a few minutes reflecting on or discussing each fact. If you are working in a group, it may help to have posters of these that everyone can refer to as they work on the proofs.

<< back to Part C: The Midline Theorem


 

Note 6

It's sometimes hard for people to separate this figure from the cutting activities they've just been engaged with. Make sure you're clear about how the figure was constructed; it might help to create it yourself. First, start with the triangle. Find midpoints D and E and connect them. Then extend that segment to twice its length. Recall what we know: AD = DC (D is a midpoint); BE = EC (E is a midpoint); DE = EF (we made the figure that way); angle DEF is 180° (we made it a straight line). That's all we know.

<< back to Part C: The Midline Theorem


 

Note 7

You may have already made a conjecture about this situation in the Take It Further section of Session 4. Now you have the tools to actually prove it.

<< back to Part C: The Midline Theorem

 

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