Why does angle theta approach angle x? The hypotenuse h approaching x is also not explained but one can imagine it geometrically. However, theta approaching x is a bit hard to visualize.

Also, feedback in general for course creators - at times the proof seems rushed and does not go into details of some steps, even though other steps are explained well.

I agree, this lecture could use some updates. I’ve submitted a request for that.

In general this course is very thin on mathematical rigor, it’s more of a “Math and Calculus Intuitions” treatment. I think the use of detailed proofs is out-of-scope for the intended audience.