[pstricks] Solving equations with pstricks (draw one-thid of an angle)

[Plamen Tanovski]

Hi,

I need to draw an one-third of an angle (\theta). Picture is here:

http://home.arcor.de/tanovski/angle.eps

To do so, I have to find the points E and D, so, that 

- E is on the circle OX

- D is on the line BO

- DE = OE = OX = r

- X, E, D are on the same line

I've looked at pst-eucl, but I can't see any way to find D and E.

Any suggestions?

best regards,
P.