Here are the types of angles, building on the previous explanation: An acute angle* measures less than $90^\circ$. It looks like a sharp corner. A right angle* measures exactly $90^\circ$. It forms a perfect square corner, often indicated by a small square symbol at the vertex. An obtuse angle* measures greater than $90^\circ$ but less than $180^\circ$. It looks wider than a right angle but not flat. A straight angle* measures exactly $180^\circ$. It forms a straight line. A reflex angle* measures greater than $180^\circ$ but less than $360^\circ$. It's the "outside" angle when two rays meet, encompassing more than a straight line.