Download I CAN write two-column proof of Linear Pair Theorem and fill in the

10/25 Bell Ringer
Step 1: Grab materials from front of the
room.
Step 2: Get out your homework and vocab
Step 3: Find the missing angle’s
measurement:
X°
X°
50°
X° 80°
Fill in vocab for Linear Pair Thm and Common
Seg Theorem. Finish today’s handout.
10/25 News and Notes
• Missing Quizzes:
– 1st: Breniah
– 7th: Brian L, Jasmine R
– 8th: Sandy, Allan, Desirae, Cristian, Ida,
Lorena, Nicole, Jasmine Z.
• Rest of week plan: M = Proofs, T = Proofs,
W = Review/Wrap-up, TH = Study habits,
F = Test
10/25 Agenda
I CAN write a two-column proof of the Linear
Pair Theorem and discuss the
importance of proving something.
1. Bell Ringer
2. New Material – Questions to consider
3. Guided Practice – Linear Pair Thm Proof
4. Independent Practice – Questions and
Proof of Common Segment Theorem.
Today’s Goal
• Get used to asking ourselves the right
questions in order to complete a proof of a
very valuable theorem of geometry.
New Material – 2 New “Tools” for
our reasoning toolkit
• Agile Mind Topic 5: Exploring: Creating
Proofs pp. 2 & 3.
New Material – Linear Pair
Theorem Questions
• Agile Mind Topic 5: Exploring: Creating
Proofs pg. 4
THE FIRST PROOF!
• Given: AXB and BXD are a linear pair
.
• Prove: AXB and BXD are supplement ary
STATEMENT
AXB and BXD are a linear pair
REASON
Given
mAXD  180
Definition of straight
angle
mAXB  mBXD  mAXD Angle Addition
Postulate
Transitive Property of
mAXB  mBXD  180
Equality
AXB and BXD are supplement ary Definition of
supplementary angles
QED!
What did we just prove?
• We took the fact that the two angles
formed a linear pair and proved that linear
pairs of angles are supplementary.
• This allows us to define the Linear Pair
Theorem:
• LPT: Two angles of a linear pair are
supplementary.
Now try on your own…
• First answer guiding questions, then
convert your answers to finish a proof.
• You must have questions answered and
have started the proof by the end of class.
• If you have questions raise your hand.
• Class disruptions will not receive credit.