1. Proofs Review

2. What’s in a Proof? Statement of the original problem
    Diagram, marked with "Given" information  
    Re-statement of the "Given" information in the proof  
 Complete supporting reasons for each step in the proof  
    The "Prove" statement as the last statement  

3. Strategies
For most proof problems, it is very helpful to examine the problem backwards -- from the "Prove" statement back to the "Given" information. 

4. Where does the conclusion come from?

5. Formal Proof Statements Reasons 1. Given
2.  Reflexive Property - a quantity is      congruent to itself.
3.  SAS:   If 2 sides and the include angle      one triangle are congruent respectively      to 2 sides and the included angles of a      second triangle, then the 2 triangles are      congruent.
4.  CPCTC: Corresponding parts of      congruent triangles are congruent.                                                           QED

6. Let’s Practice!
Look at the following examples of given information and try to come up with some ideas about what conclusions can be drawn from that information.

7. Unscramble the Proof
On the following slide is a proof from the problem below. Unscramble it with your partner.
Given:         ABCD is a parallelogram             
Prove:       DEFC is a rectangle

8. Statement Reason
In a plane, two lines perpendicular to the same line are parallel.
DEFC is a parallelogram
If both pairs of opposite sides of a quadrilateral are parallel, the quadrilateral is a parallelogram.
ABCD is a parallelogram
Given
Given
DEFC is a rectangle
If one angle of a parallelogram is a right angle, the parallelogram is a rectangle.
<DEB is a right angle
Perpendicular lines meet to form right angles.
A parallelogram had 2 sets of opposite parallel sides.

9. Homework
Continue working on your projects as outlined on ms-troast.wikispaces.com
Create a proof with a solution and bring it to class next session.
Complete 6 more sets of Khan Academy Reviews.