Postulates and Theorems Level 1
Priority Standard G-CO.9: Explain each step in proving theorems about lines and angles.
One part of this standard includes:

State and apply the postulates and theorems related to segments (2-7)

State and apply the postulates and theorems related to angles and perpendicular lines.
(2-8)
Your task: (1) To create a study guide or flash cards for each Postulate and theorem in section 2-7 and
2-8 of our textbook. (2) Memorize the theorems as indicated above. (3) Practice using the theorems to
solve geometry problems.
(1) Get note cards from me if you want to make flash cards. The theorems could be grouped.
Segments: Pg 91 Th. 2.8, Pg 102 Post 2.9 and Th. 2.2
Angles: Pg 107 Post 2.11, Pg 108 Th. 2.5,
Supplementary Angle Theorems Pg 108 Th. 2.3 and Pg 109 Th. 2.6
Complementary Angle Theorems Pg 108 Th. 2.4 and Pg 109 Th. 2.7
Vertical Angles: Pg 110 Th. 2.8
Perpendicular Lines/Right Angles: Pg 111 Th. 2.9 thru Th. 2.13
A test question for the standard will be for you to write all the theorems and postulates about one of
these categories. You do not need to remember the theorem numbers!
Example for a flashcard for angles:
Front: State the postulates and theorems for Angles (change “Angles” to “Segments” etc. for the other
cards)
Back: The sum of the measures adjacent angles is equal to the measure of the angle formed by the
common vertex and the noncommon sides. AND Congruence of angles is reflexive, symmetric, and
transitive. (you might include a diagram to help you learn it)
You have 1 class period to work on this, then the rest must be done outside of class or during work time.
(2) Study these with a partner, have them quiz you. Practice on you own until you have these
memorized. Example: Read the front of the card to your partner while hiding the back. Your
partner must do their best to recite ALL the theorems written on the back. At first give hints or
read the 1st few words to get them started.
(3) Practice problems come next session.