heights along a slope or baseline

[delboy2071]

Hi to all,
seem to be having a mad half hour and cannot seem to find what i think is a simple trig error (some-where).
will keep it short a to the point.

have a baseline of 100m long, a change in height of 10m from one end to the other.
have calculated both slope ratio and slope % with no bother e.g slope % is = 10%

now keeping in mind that when i travel along this baseline, for every 10m travelled i should rise/fall 1m so by the 100th metre i am now 10m higher or lower than from the start.

Sound easy!!!!
using base length*TAN(slope%) the answer am getting is 1.003m not 1.000m
can anyone help

 

[SteveO59L]

Tangent = opposite/Adjacent

=10 / 100

=0.1

Therefore, for a horizontal distance of 10m, the vertical distance would be

0.1 * 10 = 1m

 

[Oaktree]

Also note that your slope % is not the same as the angle. If your height is 10 and your length is 100, your angle is about 5.71 degrees (0.099669 radians).

If opposite/adjacent is small, opposite/adjacent can be a good approximation for the angle itself (consider the case of 0.1%); but, as opposite/adjacent gets larger, this approximation gets worse.

So, your tan(slope %) = 0.100335 is a pretty close approximation to tan(0.99669) = 0.1 , but it's not the same.

 

[delboy2071]

Steve,
thanks for that, seems obvious now.

was using the Tan function twice without noticing.

once again

Cheers