"Siatki" is in fact a Polish word that translates as "Nets"
For "trapezial cone" substitute "right circular cone" and call it "truncated" if you only want part of it.
For "non-prismatic/skewed cone" substitute "oblique cone"
And perhaps
https://play.google.com/store/apps/d...ecalc&hl=en_AU
looks like it might work for what you want but I haven't tried it myself since I don't need to.
Diderick
That's quite an unusual web page you have there. Does it ever manage to load fully ?