Let's assume that the road has 12 meters of rise for every 200 meters of run. The grade would be 0.06. To calculate the grade of a road with:
rise = 12 m; and
run = 200 m:
Compute the ratio between rise and run:
grade = rise/run = 12/200 = 0.06
If you want to know the angle of the slope, input the value in the arctangent function:
slope (angle) = arctan(rise/run) = arctan(12/200) = 3.43°
If you want to know the slope as a percentage, multiply the ratio by 100:
slope (percentage) = 100 × rise/run = 6%.
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