HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
Turned and flipped 18
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
HypotenuseThe side across from the right angle. It is the longest side, and it is the hypotenuse whichever angle is marked.
OppositeThis side is across from the marked angle. It is the one side that does not touch the shaded corner.
AdjacentThis leg touches the marked angle. The other side that touches it is the hypotenuse.
How this list was compiled: The three names (the hypotenuse is the side opposite the right angle and the longest side; the opposite side is the side opposite the angle in question; the adjacent leg is the other one touching that angle, the side joining it to the right angle): Wikipedia, Trigonometry, read 2026-10-01, with Hypotenuse and Right triangle; checked against Math is Fun, Sine, Cosine and Tangent, https://www.mathsisfun.com/sine-cosine-tangent.html (opposite faces the angle, adjacent is next to the angle, the hypotenuse is the long one; sine is opposite over hypotenuse, cosine adjacent over hypotenuse, tangent opposite over adjacent), read 2026-10-01. Which side of each drawn triangle carries which name was worked out by the drawing script from the triangle's corners, not by eye. Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain lines: own work. No font and nothing traced. Licence: own work
How it works
Each triangle on this sheet has a square in its right angle and a shaded wedge in one other angle. For that marked angle, name every side: hypotenuse, opposite or adjacent. The names change when the marked angle changes.
Read the full guide
Find the hypotenuse first
The hypotenuse is the side across from the right angle, the corner with the small square. It is always the longest side, and it stays the hypotenuse whichever angle is marked.
Then opposite and adjacent
Stand in the shaded corner. The side straight across from you, the one that does not touch your corner, is the opposite. The leg that touches your corner is the adjacent.
Turn the page if a triangle looks odd: the names depend on the corners, not on which way up it is.
Sine is opposite over hypotenuse, cosine is adjacent over hypotenuse and tangent is opposite over adjacent, so the labels come first.
Questions and answers
How do you label the sides of a right triangle for trigonometry?
Mark the hypotenuse, across from the right angle. Then look from the angle you are working with: the side across from it is the opposite, and the leg beside it is the adjacent.
Can the same side be opposite and adjacent?
Yes, for different angles. A leg that is opposite one acute angle is adjacent to the other. That is why each triangle here marks one angle.
Is the hypotenuse ever the opposite or the adjacent?
No. The hypotenuse touches both acute angles, but it keeps its own name. Opposite and adjacent are names for the two legs.
Does the worksheet come with answers?
Yes. Print the answer key gives the numbered sheet with the name of every side listed under it. On screen, Quiz yourself on this worksheet checks each answer as you give it.