Types of Angles
Every angle you'll encounter fits into one of five main categories based on its size. An acute angle measures less than 90ยฐ, like the corner of a slice of pizza. A right angle measures exactly 90ยฐ and forms that perfect square corner you see everywhere.
When angles get bigger, they become obtuse angles, measuring more than 90ยฐ but less than 180ยฐ. Think of opening a book wider than 90ยฐ. A straight angle measures exactly 180ยฐ and looks like a straight line, whilst a reflex angle opens even further, measuring between 180ยฐ and 360ยฐ.
Adjacent angles share a common side and vertex - they're basically neighbours sitting next to each other. Complementary angles are best mates because their measures always add up to exactly 90ยฐ. Supplementary angles are also partners, but they add up to 180ยฐ.
Quick tip: Remember "C" for Complementary = 90ยฐ and "S" for Supplementary = 180ยฐ. The alphabetical order matches the size order!