Artificial intelligent assistant

Circumscribed circle $\triangle ABC: \angle CAB = 45^o, BC = 9$. I have to find the diameter of the circumscribed circle. I thought about an hour, but I can't think up anything. I would be very grateful if you can help me! I made a drawing: ![](

$\triangle OBC$ is right angled, and $OB=OC$. You'll be able to find the radius.

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