Hi folks

I'm trying to reproduce the function of the AutoCAD MEASURE command to insert blocks along a polyline. I want to insert the blocks perpendicular to the curve & increment attribute values in a very specific pattern along the way.
I'm sure I'm missing something, but how do I get the angle of the line at a particular distance?
I think this has something to do with (vlax-curve-getParamAtPoint ... ) but I'm not bright enough to figure out the relationship.

Thanks in advance.