capnrefsmmat/khan-exercises — comment on commit dcf76a0258e3fe66a6a802eb85dc5ab800815227
File: exercises/dot_products.html line 54
By smenks13:

This is an excellent problem type (finding the angle between vectors), but I actually think it deserves its own module. It's quite a bit more complicated, as you first have to find the lengths of the vectors, and then use inverse trig to find the angle. My recommendation is to move the code for this problem type over to a fresh page, and I think this one will act as a great introduction to dot products (visually and computationally).