Parallelograms (I)

[color=#000000]Please use these applets to help you complete the [/color][i][color=#0000ff]Parallelogram Investigation[/color][/i][color=#000000] questions given to you at the beginning of class. [/color]
Sides of a Parallelogram
Interior Angles of a Parallelogram
Diagonals of a Parallelogram

Quadrilateral Angle Theorems

Interact with the app below for a few minutes.  [br]Then, answer the questions that follow.  [br][br]Be sure to change the locations of this quadrilateral's vertices each time [i]before[/i] you drag the slider!
Into how many non-overlapping triangles were we able to split this quadrilateral?
What is the sum of the measures of the interior angles of [i]each triangle[/i]?
Use your responses from the two questions above to [b]determine the sum of the measures of the interior angles of this quadrilateral. [/b]
What is the [b]sum of the measures of the exterior angles[/b] of this quadrilateral?

Parallelogram: Theorem 1

Interact with the applet below for a few minutes. [br]Then, answer the questions that follow. [br][br]Feel free to move the BIG WHITE POINTS anywhere you'd like! [br][color=#ff00ff]You can also adjust the size of the pink angle by using the slider. [/color]
1.
What special type of quadrilateral was formed in the first half of your sliding-the-slider? How do you know this?
2.
What else can you conclude about this special type of quadrilateral? Be specific!
3.
Write a 2-column, paragraph, or coordinate geometry proof of what you've informally observed here. (Hint: If you choose a 2-column or paragraph proof, this proof will involve a pair of congruent triangles!)
Quick Demo: 0:00 sec to 0:33 sec (BGM: Andy Hunter)

Information