caballero,

Very clever, Gunther , thank you.

thank you. But I had some help.

Matthäus (Mathes) Roriczer (approximate dates 1435-1495) first set this question. At the same time, he has formulated appropriate solution hints.

I just needed to draw this for everyone clearly to understand and translate it into a halfway readable English. I hope I have succeeded in doing that. That's all I have done. Everything

else is from the old master Roriczer and not from me. I give credit where credit is due. We should look with more humility at the work of our forefathers. We can see further only because

we stand on the shoulders of giants. Some people - even in our forum - seem to have forgotten that. But that's another story perhaps for a new thread when the time is ripe. I think that

you and I agree on this point.

It didn't occur to me to get out of the box because I couldn't see the triangle.

Yes, that's exactly the first trick. Therefore I've clarified it in the second sketch. I drew this by hand because I was too lazy to generate it with PSTricks. But I hope the essential nature

of the matter is still recognizable.

Also it is very useful to see that the black shaded areas are equal so that it is useful for us to subtract the area of the triangle from the third of the circle.

Yes, that's the second trick. After that, the rest is actually pretty trivial and pure hand tool. Choose an appropriate method to solve the linear equation system and solve it. That's all.

The sketches led to the core of the problem. That's often the case. Behind many complicated-sounding mathematical definitions and theorems lie simple geometric facts. Not for nothing

it's said: The language of modern mathematics is geometry.