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The Case of the Missing Diagram - Lesson 4-2

Today, we talked about how to set up proofs for which you are not given a diagram or the "given" and "prove" statements.  You should be able to do these, so make sure you follow the logic here.  We started with the following problem:

Now...don't freak!  Think about what we know from the statement and what we need to prove.  We know that two altitudes of a triangle are congruent, right?  So, that means we have a triangle and two of its altitudes in our diagram.  We also know that the altitudes are congruent.  From this, you should be able to show the following:

Now all we need is the "prove" statement.  It's what comes after the "then" in the original statement:  "the triangle is isosceles."

We then went over a few more examples...you should be able to follow these and the ones we had for homework!!  If you don't, then ask a friend, come see me, or study them until you do.  There will be one of these on the test!!!

You should be able to do the proofs for these as well...in fact, they should be getting easier for you.