1. Properties of Parallelograms
2 pairs of opposite sides parallel

2. Parallelogram
What else do we know about parallelograms because of the definition, could you prove it
Consecutive angles supplementary – SSI
Opposite sides congruent – Prove Triangles CPCTC
Opposite angles congruent – CPCTC or repeated SSI property

3. Diagonals of a Parallelogram
What do you think is special about the diagonals of a parallelogram? Are they perpendicular like a kite? Are they congruent like a trapezoid? Do they bisect each other or the angles?

4. Remember Parallel Line Properties
Corresponding - congruent Alternate interior – congruent Same Side Interior - Supplementary

5. Proof Given: ABCE is a parallelogram
Prove: diagonals bisect each other
What triangles are you going to use?
What exactly do you have to show to prove they are bisected?

6. Example – shapes are parallelograms

7. Vectors – brief examples
Vector – is a quantity that has both magnitude and direction
Describe velocity, acceleration and force
Represent a vector by drawing an arrow
Length and direction of arrow represent the magnitude and direction of the vector
Resultant vector is the combination of the two vectors on a single figure (sum vector)
To find the resultant vector you use the two vectors to make a parallelogram and construct the diagonal

8. Example
How would you draw the diagonal if these are two sides of a parallelogram?
1. Construct the other sides of the parallelogram using the arrows as endpoints or
2. Draw a diagonal between arrows, bisect it and connect vertex to midpoint

9. Homework
Pg and 13 Honors 10, 11