Tuesday, February 5, 2008

Unit One for Proofs - Angles and Lines

The addition Postulate:

If a = b and c = d, then a + c = b + d

The Partition Postulate:

AB + BC = AC

These are two different concepts. Let's try a proof:

As you can see, in step 2, we added equal quantities to each other. This is Addition Postulate.
But in step 3, we added a part plus a part equals a whole so this is Partition.
Let's try another example:
Here we used the Subtraction Postulate: subtracting equal quantities from equal quantities.
In step 3, we had the whole minus a part equals a part. This is still Partition Postulate.