A 30 degree slope equates to a slope steepness of about 3,048 feet per mile.
In a nutshell, we are talking about the angle made between C and A. C is the slope you are hiking/climbing/walking up. B would be the elevation change.
--Amin
Or, to put it in a different perspective, if the Whitney Trail were 30 degrees for the entire 11 miles, you'd finish at about 42,000 feet elevation instead of 14,500 - about 2.5
miles higher than Everest.
Conversely, at a constant 30 degrees you'd make the Portal to the summit in a tad over two miles.
Both are scary thoughts . . .