All About Angles
An angle forms when two rays meet at a common endpoint called the vertex. Angles come in different sizes: right angles measure exactly 90°, acute angles are less than 90°, obtuse angles are greater than 90°, and straight angles measure 180°.
When two angles have the same measure, they're congruent angles. Adjacent angles share both a common side and vertex - they're right next to each other. The Angle Addition Postulate states that if angles are adjacent, their measures add together to form the larger angle they create.
An angle bisector divides an angle into two equal parts. When lines intersect, they create pairs of vertical angles across from each other. Here's something cool: vertical angles are always congruent!
Remember this: You can identify angle types by thinking about a clock - right angle is at 3:00 (90°), acute is before 3:00 (less than 90°), and obtuse is after 3:00 but before 6:00 (between 90° and 180°).