The Line From Tangent and Line From Perpendicular Civil 3D commands
Jerry Bartels of Autodesk demos the classic Line From Tangent - LINETANGENT and
Line From Perpendicular - LINEPERPENDICULAR tools in Civil 3D.
From the Jerry's YouTube Channel.
and the Civil Imersion blog.
If you're like me, you too forget about the oldies but goldies all the time and then bang your head on the keyboard.
Remind yourself to review the Ribbon Draw Panels when you install an Update.
See the Recorded Line Work in Civil 3D and
related posts for the most of many improved tools for segment creation.
Of course you don't need these to create tangent from alignment segments?