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# Equation Editor Syntax - Arc length = radius * angle

matthew_stacy
Member Posts:

**66**PRO
in General

I'm having trouble entering a formula into a sketched length dimension. The intent is to set the length of the construction line segment equal the length of the adjacent arc, from variables #R and #theta (millimeters and degrees, respectively). The correct result should be approximately 34.9mm (same as the arc length).

The formula should be the product of radius and swept angle (with the angle expressed in radians not degrees):

- #R*#theta*PI/180, (multiplying by π radians per 180 degrees to convert the angle from degrees to radians)

**conversion, peppered with**

*PI/180**and*

**rad****in every conceivable location. Could someone please provide the correct syntax for this expression? So far I keep running into the**

*deg***.**

*Enter a valid expression prompt*Here is a link to the document: https://cad.onshape.com/documents/ba77da0d35372c64be7be8bf/w/10b3901e704eabe14945dea2/e/482389f1f55cb0146b53c145

0

## Comments

3,25466PRO99266PROFrom the perspective of dimensional analysis I've got the product of length (mm) and angle (degrees), but need to convert the angular unit to radians. Is /radian code for a function call to "convert #theta from degrees to radians"? That is not intuitive to me.

992Similarly, if you have a length and need to know how many millimeters it is, you would do #myLength / millimeter. For example if #myLength is 3mm, you would get: #myLength / millimeter = 3 * millimeter / millimeter = 3.

Hope this helps.

66PRO99266PRO