A/H = Cos (alpha), where A is adjacent side in mm units, H is hypotenuese in mm, and alpha is the angle between them for a right angle triangle.

But Revit doesnt seem able to do this despite having the functionscos(), and acos()I assume

acos()returns a result in angular degrees, whereas the sides are in mm.

No matter how I try to set up this formula in a family parameter, I get an 'inconsistent units' error.

A and H are in units of length, but alpha is in units of degrees.

If I use alpha = acos(A/H) I get a 'Cannot evaluate function' error.

So I assume I have to neutralise the mm/mm which is presumably then unitless by multiplying by degrees.

There seems to be no way of saying that.

I have tried setting up a parameter as an angle of 1 degree and multipling by that, or even dividing by that, but still get 'inconsistent units' error.

Have searched the forums and internet generally...lots of people seem to want an answer to this, but no one seems to have ever answered!

So does anyone know how trigonemetry can be used in Revit to derive the angle between two sides of a right angled triangle as a formula in a family parameter?

Can you give an example?

Does anyone know what unitangleneeds to be expressed in , ie like mm or m for length?

Hope someone can tell me how to do this.

Thanks, Robin