1b - lesson 9 and 10 - proofs.notebook · 2018. 10. 16. · 1b lesson 9 and 10 proofs.notebook 11...
TRANSCRIPT
1B Lesson 9 and 10 Proofs.notebook
1
October 16, 2018
Copy this picture. Label any extra angle that would help you solve it.
Do not solve.
x 42
88book open to p 99 100
1B Lesson 9 and 10 Proofs.notebook
2
October 16, 2018
Warmup Where did you put the extra angles?
book open to p 99 100
1B Lesson 9 and 10 Proofs.notebook
3
October 16, 2018
2
1B Lesson 9 and 10 Proofs.notebook
4
October 16, 2018
dual
1B Lesson 9 and 10 Proofs.notebook
5
October 16, 2018
3
1B Lesson 9 and 10 Proofs.notebook
6
October 16, 2018
dual
1B Lesson 9 and 10 Proofs.notebook
7
October 16, 2018
4
1B Lesson 9 and 10 Proofs.notebook
8
October 16, 2018
dual
1B Lesson 9 and 10 Proofs.notebook
9
October 16, 2018
4 2nd way that many students do
1B Lesson 9 and 10 Proofs.notebook
10
October 16, 2018
So what if we don't have a specific case (one with numbers) to model our proof off of?
another analogy
Proofs are like puzzles.
How do you know what a puzzle is supposed to look like?
So we look at the picture and find all the pieces that have the Coca Cola words. Then what?
So we look at the picture and find all the pieces that have to do with the starry sky. Then what?
We need to put those two pieces together to find the overall picture.
Writing a proof is the same way.
We look at the equation we want at the end to see where we need to start.
Then we see how we can introduce each variable based on what we have in the picture.
1B Lesson 9 and 10 Proofs.notebook
11
October 16, 2018
Proving things creates new reasons.
These new reasons let us do in one step what might otherwise take many.
The ones we did on p 99 100 are situations we won't see too often.
But, the reasons we use all the time (p 53) can be proven too.
1B Lesson 9 and 10 Proofs.notebook
12
October 16, 2018
We want to Prove x + y = z
What do we know about this picture?
What types of intersections apply?
(without using exterior angles of a triangle)
We want an x in our equation. What simple part of the picture is x part of?
We want a z in our equation. What simple part of the picture is z part of?
p 96The puzzle box. I know it needs to look like this at the end
This gives us everything we need, now we just need to put the pieces together.
("solving the system")
Making sure our finished puzzle looks like the box
We want to Prove x + y = z
1B Lesson 9 and 10 Proofs.notebook
13
October 16, 2018
p 97Prove: w + x + z = 180 Prove: w + x + z = 180
1B Lesson 9 and 10 Proofs.notebook
14
October 16, 2018
Exit:
Why does the thing we're trying to prove appear at both the beginning and the end of the proof?