Angle Addition Postulate Classify angles 1.4 Angles and Measures Angle Addition Postulate Classify angles

Definition of an angle Two rays that have the same initial point called the Vertex Named ∠ABC A All angles are named with three letters. B The middle letter is the vertex. C

Angle Measure We use a protractor to measure angles and is given a letter m before the name when standing for its measure. m∠ABC = 50ᵒ, so the angle has a measurement of 50 degrees.

The Protractor Postulate like the Ruler postulate for angles The measure of an angle is the absolute value of the different of the terminal side and the initial side. X terminal side 50 ᵒ Y Initial side Z

Angles can be also be Congruent Again the definition of Congruent is Same Shape and Same Size. If m∠XYZ = m∠ABC, then ∠XYZ≌∠ABC. If ∠PQR≌∠FMB, then ∠PQR≌∠BMF, but not ∠PQR≄∠MBF. Order is important! The vertex must be in the middle

Angles have an Interior and an Exterior K Q Interior Exterior X

The Angle Addition Postulate If P is in the interior of ∠RST, then m∠RSP + m∠PST = m∠RST T m∠TSP = 12ᵒ P m∠PSR = 24ᵒ S R m∠RST = 36ᵒ

Classifying Angles Acute Right Obtuse 0 to less then 90ᵒ degrees More then 90ᵒ degrees 90ᵒ degrees Straight Angle equals 180ᵒ

Adjacent Angles Adjacent means next to each other; the same as adjacent lockers. Adjacent lockers share one wall. Adjacent angles share one side and have a common vertex. ∠ABC and ∠CBX are A C adjacent angles B X

Homework Page 29 – 31 #17 – 22, 26- 34, 38, 41, 42, 51-53