Returns the angle between this vector and the specified vector. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
Syntax
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| Visual Basic | 
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| Visual C++ | 
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Parameters
- source
-  Type:  Autodesk.Revit.DB XYZ  
 The specified vector.
Return Value
The real number between 0 and PI equal to the angle between the two vectors in radians..Remarks
 The angle between the two vectors is measured in the plane spanned by them. 
 Exceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentNullException | Thrown when source is a null reference ( Nothing in Visual Basic) . |