Maybe a dumb question: for arc tangential to a line, don’t you need radius and degrees?

I hope that this is not a dumb question - maybe I don’t understand the geometry?

I have been reading the documentation for “Arc Tangential”, and the documentation says that the command takes either a radius or a number of degrees.

Don’t I need both?

Couldn’t I have a 15 degree arc of radius 36” tangential to a line, and also have a 35 degree arc of radius 16 degrees tangential to the same line?

Just try out the feature. In the Tools Options bar above the drawing area you are asked for either a radius or an angle, additionally you are asked in the command line to specify an end angle or an endpoint respectively.