My recollection is that we were taught the hypotenuse rule earlier in the year, might have even been just before trigonometry, but I have no recollection of bei

My recollection is that we were taught the hypotenuse rule earlier in the year, might have even been just before trigonometry, but I have no recollection of being informed of any "connection" between them during school. We were simply taught which equation to use for particular scenarios and how to use calculators with particular equations. When you bought it up, I do recall the connection being used by Open University to explain things, which I also found a bit thrilling to learn. Although only anecdotal evidence, I have asked a few South African colleagues over the years about the unit circle and it seems like none of them were taught it during school, so it seems like it's just not in the curriculums over here, which I feel is a tragedy.