I'm trying to understand how my book derives the tangential accelration. I drew a picture because it's kind of confusing to explain. From the triangle we get the tangential and normal components of the velocity. What my problem is (and I think, and hope, it's something simple that I just can't see) that in the second equation where they find SQ. They times they take adjacent x sin(angle) = oposite. but isn't sin = oposite/hypoteneuse ?? shouldn't the formula be adjacent x tan(angle) = opposite = SQ ?