Originally posted by fire_ant:
The number after the slash is the degrees of slope. I’m not sure what the precise formula is for determining how slope effects penetration
There is none, especially since the armour & ammo quality varied. Looking at the various frontal armour degree values in you post I wonder if there is a mix-up in the table.
There used to be two different methods of measuring the angles. The one I'm more familiar with is the (continental?) european one - 0 degrees is flat horisontal, 90 degrees is vertical. The other system has it reversed.
T-34 frontal armour is not 60 degrees, it is more like 40. On the other hand, Sherman's frontal armour is quite steep (and high), almost 60 degrees.
So, figures from various sources cannot always be compared without checking them first.