Hi @ferdinand !
Sorry for late reply, and thank you very much for your detailed and thorough explanation, and for taking the time to explain the relationship between linear algebra and trigonometry in the context of computer graphics and transformations.
As a beginner, all I want to do here is to practice as much as I can with the knowledge I've learned, and I apologize if I didn't explain clearly.
Yes, in the code I want to implement is placing two tangent handle relative to the two input objects a and c.
Compared to calculating with trigonometric functions, your suggestion seems more straightforward and clear, and I never would have thought to use vectors to achieve this, I need to keep practicing.
I will take the time to review the thread you mentioned.
Thank you again for your support and guidance. Thank you very much for your insights!