In the Raster Calculator: sin(angle)
The "angle" must be in radians; therefore, the correction to your formula would be:
(Power((("FlowAcc" * 92.46745509) / 22.13),0.4)) * (Power((Sin("Slope_Degree" * 0.01745 / 0.0896)),1.3))
Please let me know if it works.
I tried and installed the GISus_M esri add-in in Arcgis 10.2, however, it's not functional. Just it's only installed and also showing in Arc tool list, but not highlighting any the options in the model. Kindly suggest me right procedure for installation in order to work on the model.