My textbook says "A is the area of the circle enclosed by the current" (produced by an electron in a hydrogen atom), A = ##\pi r^2 \sin(\theta)^2##. I don't understand where the ##\sin(\theta)^2## comes from.
Here, I disagree with you. I'm a second year physics student, and I find myself in the exact same situation as the OP. I naturally understand physics concepts, but math (and the way it was taught to me) holds me back.
In my first year we had some advanced math courses and nothing of it made...