Everyone is making this soooo hard.
A partial circle tangent to two lines or two arcs or one line and one arc.... is a Fillet. A Fillet is an arc tangent to 2 entities. In your options you can also make it a Full circle if you want (look at the options on the ribbon bar. Its the pull down that says Normal).
Select Fillet - Enter your Radius - Pick your 2 elements.
Mike Mattera
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