quota from the apex

[deep70]

Hello everyone,
simple question I imagine for most of you..
I have to quote correctly from the apex or angle crossing given by a sheet with a bend of 45°.
place a couple of image where I put the odd in incorrect position in the first to better make the concept, while for the second I extended the edges through sketch.
thanks to all in advance for the answers given.

 

[Cast16]

Take a look at this video

 

[deep70]

thanks many cast16, I must say that the system is a little laborious but the only possible. . I have been of great help many thanks again and good evening to you.