Reply To: How to enable the constraints of tangent line tool?

[Atharv Joshi]

Hi Felipe, 

In this video the instructor is using the Change Angle feature with the reference construction line.
You can perform the same operations using Dimension Tool from Design Tab while sketching.

First add the diameter for circle as shown. 
Select the tangnet and construction line to add the angular dimension as per drawing. 
Later on you can use "Create Corner" to extend the tangnet line to the edge. 

 

Thanks and Regards
Atharv