[VAC] Re: Grade %

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx>]

The mathematical relationship is that tangent( angle) = rise/run.
Surveyors measure rise with a level and rod, and run with a tape. So %
grade is simply 100 * rise / run. Far simpler to compute than angle. And
at low slopes, under 5 or 6%, slope and angle are essentially the same
for the angle in radians. There 360 degrees in a circle and 2 pi (=
6.28) radians. At 1 degree slope, slope (not %) is 0.017455. The angle
in radians is 0.017453. There are (360/ 2 pi) 57.29578 degrees per
radian. End of math lesson.

Gerald J.