Posted by **?** on Wednesday, October 22, 2008 at 8:27pm.

HELP!!! I am soooo lost.... I don't understand anything....I can't really show what I am doing because it has a picture but the direction is:

Show an organized proof with justification for every step. Given:Parallelogram ABCD Prove: angel 1 + angel 2= 180 degrees...

if someone can explain what I am suppose to do I really appreciate it... there is like a graph to it that looks like a tick tack toe board...

- Geometry 2020 -
**Damon**, Wednesday, October 22, 2008 at 8:39pm
Draw the parallelogram with top and bottom horizontal and the left and right edges slanted up to the right.

Draw the lines at the edges out beyond the parallelogram.

Now look at the more or less vertical edge on the left.

Call the lower inside angle = A

Now that left edge goes up and crosses the top edge of the parallelogram.

The upper right angle at that intersection at the top will also be A because a line crossing two parallel lines forms equal interior angles.

But that angle plus the angle inside the parallelogram at that upper intersection form a straight line, the left edge of the parallelogram.

Two angles that add up to a straight line are supplementary, they add up to 180 degrees.

- Geometry 2020 -
**Damon**, Wednesday, October 22, 2008 at 8:40pm
Once you do that you can do it for any of the corners if your drawing looks different.

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