# incenter and orthocenter

#### Albert

##### Well-known member

Last edited by a moderator:

#### chisigma

##### Well-known member
What I see before 'attacking' the problem is that, without any serious failure of me, the 'demonstration' [if any...] would also demonstrate that trisection of an angle with only non graduate ruler and compass is possible... or not?...

Kind regards

$\chi$ $\sigma$

#### Albert

##### Well-known member
trisection of an angle with only non graduate ruler and compass is possible... or not?...
It is impossible to trisect any angle with only non graduate ruler and compass ,but some angles are possible, and this is unrelated to this problem .

Last edited:

#### caffeinemachine

##### Well-known member
MHB Math Scholar
I need to show that the angle between $CH$(extended) and $HI$ measures $\frac{\angle B}{2}$. I am trying to give a purely geometric proof of this. Any hints on these lines?