Dear friends

I have doubt on generation of slope

Problem: two different output of slope in degree

Data: SRTM DEM 90m

Process 1: Slope is generated using DEM --spatial analyst tool--surface--slope

Here output slope is generated showing the slope in degree from 0 to 61 degree

Process 2: Slope is generated using DEM -- Contour (20M) -- TIN- TIN to raster and this raster is used to generate slope

Here output slope is generated showing the slope in degree from 0 to 34 degree

So my problem is which accurate method is?

Thanks