Name Definition Visual Clue Angle Addition postulate For any angle, the measure of the whole is equal to the sum of the measures of its non-overlapping parts Linear Pair Theorem If two angles form a linear pair, then they are supplementary. Definition and properties of a linear pair of angles - two angles that are adjacent and supplementary. Proof. Addition Property: If a b= , then a c b c+ = + 2. In such a case, all adjacent angles form a linear pair. 4. Rays OA, OB, and all the rays with endpoints O that can be drawn on one side of line AB can be paired with the real numbers from 0 to 180 such that OA is paired with 0 degree and OB is paired with 180 degrees. Statements Reasons 1. Two angles are said to be linear if they are adjacent angles formed by two intersecting lines. linear pair. Postulate 1-3 Two lines intersect at exactly one point. 3. In the figure, ∠ 1 and ∠ 2 form a linear pair. Given: <1 and <2 form a linear pair. Subtraction Property: If a b= , then a c b c− = − 3. Linear Pair Theorem If two angles form a linear pair, then they are supplementary. Postulate 1.8 or angle addition postulate Postulate 1-2 A line contains at least two points. Definition of a linear pair 3. Theorem 2-3 Example: Because