It never affected the width, just the range. There used to be a different range enhancement for cones, but those were removed and normal range enhancements were changed to work for cones as well.
Hmmm, i could have sworn range affected width of cones as well. Maybe my memory is leacking - sounds familiar? 
-, but I could have been wrong there. So they certainly don't extens width according to you max?
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There used to be a different range enhancement for cones, but those were removed and normal range enhancements were changed to work for cones as well.
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Way to misread, Blue_Note 
Still my memory makes me believe range enhancement worked that way. But i'll go with the almighty Max' inspiring words 
As far as I thought the Angle of the cone remains the same, just the lenght of it changes.
So the end edge width does increase, they act like Similiar Triangles, at least as far as I thought.
Could be wrong of course. Its not exactly well documented!
What Carnifax said. Making the cones longer naturally makes them wider at the broad end. Thus, range enhancements are good bang-for-buck in cones, particularly broad ones (Flamethrower, Tenebrous Tentacles, etc)
This was my understanding, I remember it being discussed when they merged the two enhancement types, and from the occasions I've slotted range in cones I'm pretty certain it's right. Of course it's hard to give a definite answer without some very specific and tricky to set up testing which I haven't done, but it certainly appears to be.
If you want your cone to be wider use it at the edge of it's range - of course that is true whether you extend the range on it or not.
Mathematically it does work that way indeed, hence it's worth to use a cone attack at it's edges. Still you want to hit as many mobs as possible in depth as well, so it's kinda tricky to use it as it's most efficient.
I just remembered and dug up this saying cone enhancements do widen the cone:
"Slotting: Since Night Fall attacks in almost a straight line, I recommend sticking a Cone Range in there to widen the cone a bit, reducing the distance you have to step back to affect mobs. The rest should be damage, since a well-slotted Tentacles -> Nightfall -> Tentacles -> Nightfall is enough to kill most yellow minions, and oranges require an extra Tentacles"
From this good, but rather old guide.
I am talking about this for personal use -and usefullness- of range ehancements in nightfall and firebreath. The latter has such a small cone- a so silly small one that it's is actually not fair when you compare it to other cone attacks. (good thing to boost in next issue 
Finding this guide again still makes me wonder about the cone enhancements. I've been testing this, but it's hard to get a good look at it.
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I am talking about this for personal use -and usefullness- of range ehancements in nightfall and firebreath. The latter has such a small cone- a so silly small one that it's is actually not fair when you compare it to other cone attacks.
[/ QUOTE ]Fire Breath has a good sized cone. You're most likely thinking of Breath Of Fire (The tank/brute version)
Fire breath is a long cone but I find it a bit thin and difficult to lose.
Since range enhancements are 20%, the end of a cone is 20% wider. The cone angle stays the same.
IN MEMORIUM OF GAYBABY
CRUELY TAKEN FROM THIS WORLD WHILE SO YOUNG
I meant fire breath, but the keyword is latter: meaning i was talking about tthe VERY narrow cone of nightfall.Fire breath has pretty good cone indeed.
Wondering if hero builder got the maths right saying nightfall has 20 and firebreath 30 degrees. If firebreath has indeed 30 then nightfall must have something like 14 in comparison when firing it of... 
Can anyone say wether range slots in cone attacks widens the cone ?
)
It used to work like that long time ago, but i can remember vaguely that they removed that effect in some patch long time ago so range enhance only would affect the depth (range) and not the width of the cone anymore... (linky of patchnote maybe?
Been looking on the forums, but as we all know the search option is very bad