Originally Posted by
Turboem1
It depends if you use the sine function (opposite over hypotenuse. elevation gain over actual distance traveled) or if you use the Tangent function (opposite over adjacent. elevation gain over horizontal distance.)
In real world cases they come out very close to each other but in extreme cases they begin to differ a lot.
I started to add you can get a hell of a lot more complicated about it, but simply rise/run works pretty well for cycling purposes