Help with a Geometry Problem - Calculating The Radius of a Curve

[tomtomtom1]

Hello all

I work in transport engineering. i have come across what seems to be a simple maths problem but i do not understand it.

The problem relates to geometry i.e. calculating the radius of a curve using a chord and a versine.

The problem is this:-

" a general rule of thumb is as follows: with a chord length on 20m, the versine measured in mm (v) divided by 50000 gives the radius in meters (R) i.e. v=25mm -25/50000=2000-R=2000m"

when i work this out i do not get 2000m. also the problem shows a -25 it could be a minus or just a dash i cannot be sure.

Can anyone shed any light on this?

Thank you for your help

 

[Integrand]

Hello all

I work in transport engineering. i have come across what seems to be a simple maths problem but i do not understand it.

The problem relates to geometry i.e. calculating the radius of a curve using a chord and a versine.

The problem is this:-

" a general rule of thumb is as follows: with a chord length on 20m, the versine measured in mm (v) divided by 50000 gives the radius in meters (R) i.e. v=25mm -25/50000=2000-R=2000m"

when i work this out i do not get 2000m. also the problem shows a -25 it could be a minus or just a dash i cannot be sure.

Can anyone shed any light on this?

Thank you for your help

Well, your confusion is justified. It's an incoherent mess. None of those minus signs is a minus sign. Check the page www.mathopenref.com/arcradius.html and you should understand what is happening. Following the symbols used on that page, plug in a versed sine of H=25mm and a chord length of W=20m and you get the desired result of R=2000m.