I have point data set and DEM and my task is to identify how many points are falling on the slope of more than 40 degrees. How could I do this in ArcMap?
If you have the spatial analyst extension then you will first need to calculate the slope of the DEM. Make sure you select your DEM as your input and select the output measurement to Degrees.
You can then use the Extract Values to Points tool to extract the raster value to the point data. It should create a new field which by default is called "RASTERVALU".
You could then use an expression to select all points which are greater than 40 degrees within ArcMap or just export the data table into Excel and do your analysis there.