Quick Summary: Now that segments were covered in the last lesson, you'll now move onto angles, describing relationships of angles, and classifying them.
key terms
Angle - a figure formed by two rays, or sides, with a common endpoint called the vertex. The set of all points between the sides of the angle is the interior of an angle.The exterior of an angle is the set of all points outside the angle.
Acute angle - measures greater than 0° and less than 90°
EX: The angle is acute because it measures 45° which is more than 0° but less than 90°
Right angle - measures 90°
Obtuse angle - measures greater than 90° and less than 180°
EX: The angle is obtuse because it measures 130° which is more than 90° but less than 180°
Straight angle - formed by two opposite rays and measures 180°
Congruent angles - angles that have the same measure.
EX: <A and <B are congruent angles because they both measure 48°
Adjacent angles - two angles in the same plane with a common vertex and a common side, but no common interior points
EX: <1 and <2 are adjacent because they share the same vertex (point B) and a side (segment BC)
Linear Pair - pair of adjacent angles whose noncommon sides are opposite rays
EX: <ACD and <DCB are linear pairs because their noncommon sides (ray CA and ray CB ) are opposite rays
Complementary angles - two angles whose measures have a sum of 90°
EX: m<ABC (15°) + m<CBD (75°) = 90°
Supplementary angles - two angles whose measures have a sum of 180°
EX: 45° + 135° = 180°
Vertical angles - two nonadjacent angles formed by two intersecting lines
EX: <DPA and <BPC are vertical angles
Naming Angles
Measuring and Classifying Angles
Using the Angle Addition Postulate
Finding the Measure of an Angle
Identifying Angle Pairs
Finding the Measure of Complements and Supplements