How to write mathematical equations in relation dialog box, such as cuberoot, cot, tan, cosine etc??

It should all be explained in the help section under expressions.

I am not sure about the cuberoot value.

I don't see cubed root, but this should give you everything else:

http://support.ptc.com/help/creo/creo_pma/usascii/#page/fundamentals%2Ffundamentals%2Ffund_seven_sub%2FAbout_Functions_Used_in_Relations.html%23

R1max = 0.505 * d1 + 0.069*d1^(1/3)

ds = p * cos ( tau / 2 ) / sin ( tau / 2 ) - 1.04 * g1 - 0.76

The only term I'm not sure of is the fractional "power", "^(1/3). I've never had need to use such an expression. You should also take a look at the reference materials people have suggested. The syntax is similar to most programming languages with respect to operator precedence, etc.

All "variables" above ( such as "tau", "d1", "R1max", etc.) are assumed to have been defined as parameters or model dimensions.

This sounds like an excellent case for using an embedded Mathcad worksheet instead of Relations.

Mathcad Express is free from PTC, and no additional licenses are necessary to embed a worksheet. This functionality is available from the Applications tab.

Unless I'm mistaken, these equations are of fundamental importance in the urine extraction process.
Or as we call it in Scotland, taking the piss!

??

Hi, for power and root functions the format is ^x and ^-x, so cube root will be ^0.333 or ^1/3