HU is the hypotenuse! - IU is the opposite side of angle H - and i'm pretty sure HI is the adjacent side to angle H! -the hypotenuse is always the longest side and will be the opposite side of the right triangle. so angle i is the 90 degree angle, so the opposite side is HU which is also the longest! - angle H is marked and you can see the opposite side of it is IU which is one of the legs of this triangle. - adjacent just means like next to or beside so the side HI is next to the angle H which is also a leg of this triangle. i hope this helps!!