Note: I recommend that this page be printed out, so that the instructions are easier to follow.
In order to successfully complete a proof,
it is important to think of the definition and the construction
of a parallelogram.
In the following outline, I will provide the statements, you provide the reasons.
Prove: *If a quadrilateral is a parallelogram, then the consecutive angles are supplementary.
Given: Parallelogram ABCD
Prove: Angle BAD and angle CBA are supplementary. *This is a proof for a single pair of consecutive angles. To fully prove the statement above, the 3 other pairs of consecutive angles must also be proved to be supplementary.
If you have any questions while trying to complete this investigation, or suggestions that would be useful, especially for use at the high school level, please send e-mail to firstname.lastname@example.org.
Return to the Table of Contents.