1. Unit 2: Intro to Geometry Day 6
2-4 Algebra Proofs
2/11/2013

2. Agenda
Warm-up
Homework Check
Quiz
2-4 Algebra Proofs
Practice/HW

3. Warm-Up 2/11/2013 If possible, Draw a conclusion:
If a number is a multiple of 16 then it is a multiple of 8. If a number is a multiple of 8 then it is a multiple of 2.
If two angles are congruent then they have two equal measures. <m and <p are congruent.

4. Homework Check A)If you hear thunder, then you see lightning.
B) if you do not see lightning, then you do not hear thunder.
C) If you do not hear thunder, then you do not see lightning.
A) If a triangle has on angle greater than 90, then the triangle is an obtuse triangle.
B) If a triangle is not obtuse, then it does not have an angle greater than 90.
C) If a triangle does not have an angle greater than 90, then it is not an obtuse triangle.

5. 3. A) If a # is an integer, then it is a whole # B) If a # is not a whole #, then it is not an integer. C) If a # is not an integer, then it is not a whole #. 4. A) If 2 segments are congruent then they have the same measure. B) If two segments have the same measure then they are congruent. 5. A) If an integer is a multiple of 10 then its last digit is 0. B) if an integers last digit is 0 then it is a multiple of two planes intersect if and only if they form a line. 7. a number is an even number if and only if it ends in 0, 2, 4, 6, or 8.

6. 2-4 Algebra Proofs
Algebra Properties: If a=b, then… a+c=b+c a-c=b-c ac=bc
Addition property of Equality
Subtraction property of Equality
Multiplication property of Equality
Division property of Equality
Have students tell the “name” of the property

7. Distributive Property: a(b+c) = Reflexive Property: a=a, Symmetric Property: If a=b then b=a Transitive Property: If a=b and b=c then a=c Substitution Property: If a=b then a may replace b

14.  Homework 
Worksheet