Adjacent angles are next-door neighbours: they share a vertex and one whole side, and they don't overlap. Together they make a bigger angle.
Drag the ray
130°
obtuse angle
supplement = 50°
The three tests for 'adjacent'
- Same vertex — both angles start from the same point.
- Share a side — one arm is common to both.
- No overlap — they sit beside each other, not on top of each other.
Adjacent angles on a straight line are supplementary (add to 180°). Adjacent angles that make a right angle are complementary (add to 90°). 'Adjacent' on its own doesn't fix the total — it depends what they sit on.
Your turn
Two adjacent angles together form a right angle. One of them is 32°. What's the other?
Watch out
Vertical (opposite) angles are not adjacent — they only touch at the vertex, they don't share a whole side. Adjacent means *side by side*.