1. ## triangle

http://img395.imageshack.us/img395/9...heangelfk4.png

all the angles are given how do u find the angle that has a question mark beside it?

2. The answer is $\measuredangle~\alpha=20^\circ$

Try it!

It's a beautiful problem.

Of course, don't even think use trig.

3. how did u get that?

4. Klicken sie Heir.

Sorry, Krizalid I used trigonometry to solve it. I am not as good in Classical Geometry as you are.

5. Here's a picture

Take a point $F$ such that $\overline{CF}=\overline{CE}~\wedge~\measuredangle~ BCF=20^\circ$

You need to prove two facts:
• $\overline{AD}=\overline{BC}$
• $D,\,E,\,F$ are collinear.
Finally, you'll see that quadrilateral $BCDF$ is cyclic, and the problem is done.

Good luck!