1. Angles
(def) An ACUTE ANGLE is an angle w/ a MEASURE less than 90° (def) A Right angle is an angle w/ a MEASURE = 90° (def) An Obtuse angle is an angle w/ a MEASURE greater than 90° but less than 180 °. (def) A Straight angle is an angle w/ a MEASURE = 180°
Interior of angle
Exterior of angle

2. To Name an Angle- either use 3 letters or number it, never use only 1 letter unless there is only one angle with that vertex. If you use three letters, the vertex must be the middle letter. A
or never use
in this type of problem since more than one angle has a vertex of B. D 1 E B

3. (def) Adjacent Angles are 2 coplanar angles that share a common ray and vertex but no common interior pts.
(def)An Angle Bisector is a ray that divides an angle into 2 congruent angles. A D C B

4. Angle Addition Postulate- If D is in the interior of , then
i.e. The sum of the parts = whole A D B C

5. (def) Supplementary angles are 2 angles whose measures have a sum of 180°
or 145° 35°

6. (def) Complementary angles are 2 angles whose measures have a sum of 90°
or 50° 40°

7. (def) Linear Pair angles are 2 adjacent angles whose non-common sides form a line.
Linear Pair Theorem- If 2 angles form a linear pair, then they are supplementary.

8. (def) Vertical Angles are 2 nonadjacent angles formed by intersecting lines1 3
Vertical Angles Theorem- If 2 angles are vertical angles, then they are congruent.