(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A parallellogram ABCD has an interior point O sucht that [tex]

\alpha + \beta = 180^o

[/tex]

http://img413.imageshack.us/img413/5636/post102741235319763.png [Broken]

Prove that:

[tex]

\angle{OBC}=\angle{CDO}

[/tex]

2. Relevant equations

Definitions of a parallellogram.

3. The attempt at a solution

I don't know how to start can some give me a hint?

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# Homework Help: Plane geometry

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