Understanding Angles
An angle forms when two sides (like lines or rays) meet at a common endpoint called the vertex. You can name angles in different ways: by just the vertex letter, by three letters with the vertex in the middle, or sometimes by a number.
Angles come in various types based on their measure. Acute angles measure less than 90°, right angles are exactly 90°, obtuse angles are between 90° and 180°, and straight angles measure exactly 180°. When two angles have the exact same measure, they're called congruent angles and are often marked with matching arc symbols.
The Angle Addition Postulate tells us that when a point is inside a larger angle, the measures of the smaller angles add up to equal the larger angle's measure. For example, if point S is inside angle PQR, then m∠PQS + m∠SQR = m∠PQR.
Quick Tip: An angle bisector is a ray or line that cuts an angle perfectly in half, creating two congruent angles. Think of it as creating a fair split between two angles!