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Slope measurement? % to degree conversjon?(4 posts)

Slope measurement? % to degree conversjon?elviento
Dec 5, 2003 11:02 AM
People use % and degrees to describe slopes. How do you convert between the two? The number of degrees is typically about half the number of %, right?
roughDougSloan
Dec 5, 2003 11:27 AM
100%=45 degrees, so you'd be about right.

I've never heard of the slope of roads being described in degrees, though.

Doug
re: Try thisSEPARIDER
Dec 5, 2003 11:49 AM
Roads are measured in % of slope. Divide rise over run then mulitply by 100 to get a whole number. EX. Road goes up 10' in 100'then you have (10/100)*100 = 10%.The quotient is actually the arctan (tan-1) trigonometric function of the angle of the road. Do your 10/100 division then hit the tan-1 function key on your calculator and the answer is spit out, probably in decimal degrees.
If you know the road is on certain degree of slope, find the tan function of that angle (enter the degrees in the calculator then hit the tan function key), then multiple by 100 to get the % of slope in whole numbers.
Quick math:Alexx
Dec 5, 2003 12:51 PM
% slope=(rise/run)*100 {also called "gradient"}

slope=rise/run=(% slope)/100

degrees=arctan slope/100

ergo, slope=tangent degrees, and % slope=(tan degrees)*100

Don't forget to put your calculator into 'degree' function. If you're in radians, you are screwed.