Formula Problem

[Doug]

I am making a cabinet door with an eyebrow top.
I am trying to add a formula for a radius based upon the rise of the arc. The formula is simple

((4 * rise * rise) + (chord * chord)) / ((8 * (rise * rise)).

I keep getting an error (Inconsistent Units) when I multiply any item together.:banghead:

What am I doing wrong?

Thanks

Doug

[PeterJ]

essentially in this formula I assume rise and chord to be length parameters.

In the formula you propose you are squaring both rise and chord so the resultant parameter is area based. This may be the problem.

You can lose it (I think) by declaring that parameter as an area, then introducing another length parameter called areacorrector and setting it to 1, if you then divide the parameter that your formula creates by the new areacorrector parameter you will be back to length. (i.e. area/length = length)

You also appear to have a problem with an extra bracket in the lower line of your formula but I assume that that is a typo here as I think Revit would trap it.

[aaronrumple]

You can also convert directly from area to length by dividing by one. (one inch or one foot depending on the situation.

For example:
Rise = 2"
(4*rise*rise) = 16 inches squared.

So (4*rise*rise)/1" = 16"

[Steven Campbell]

or simply...
((4 * rise * rise) + (chord * chord)) / (8 * (rise * rise)) * 0' 1"

[Doug]

Back from a late lunch...
Thanks!!! adding the *1 works.
Now I found a post by Bob who had an eyebrow window by Steve Buri (see attached) It appears he is using the same formula (trig Properties of a Circle)

It doesn't appear he added the additional math... What am I missing.

I just know I am going to be red faced

Doug

[Steven Campbell]

Not quite the same:
((4 * h * h) + (Width * Width)) / (8 * h)
You have the rise squared...
((4 * rise * rise) + (chord * chord)) / (8 * (rise * rise)) * 0' 1"

[Doug]

I knew I would be red faced!!!

Thanks - couldn't see the trees thru the forest... or however that goes...

Thanks again!
Doug