https://learn.microsoft.com/en-us/dotnet/api/system.windows.media.rotatetransform.angleproperty?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-9.0
RotateTransform.AngleProperty Field (System.Windows.Media) | Microsoft Learn
Identifies the Angle dependency property.
field systemwindows mediamicrosoftlearn