John Gabriel says that every straight line has a slope in terms of angle, and how do morons respond?
"But not in terms of rise/run between 2 points."
Of course, that's what Newton did. He changed the definition of slope from angle to tan (angle). See, a vertical line has a slope of 1 right angle (or 90 degrees or pi/2 radians), but is has no tangent ratio, that is, opposite/adjacent is not defined.
The slope is defined everywhere. Likewise the slope of a straight line is defined everywhere -- in accordance with John Gabriel's New Calculus definition.
Slope is defined between (0,0) and (0,1) as 90 degrees.
Derivative always means the slope of a special kind of straight line called a tangent line.
There is NO such thing as an instantaneous rate. It is a misconception of idiot mythmaticians, the likes of Gilbert Strang from MIT. Just another stupid moron compared to John Gabriel.