1. 1-3 Measuring Angles
Geometry

2. Angles can also be named by a #. (____)
Angle symbol:
2 rays that share the same endpoint (or ________ ________)
Sides – the rays XY & XZ
Vertex – the common endpoint; X Y X 5 Z
Named _______, ______ (vertex is always in the middle), or ___ (if it’s the only ___ in the diagram).
Angles can also be named by a #. (____)

3. There are 3 different <B’s in this diagram; therefore, none of them should be called <B.

4. Angle Measurement m<A means the “measure of <A”
Measure angles with a _____________.
Units of angle measurement are _________ (o).
Angles with the _____measure are congruent angles.
If m<A = m<B,
then <A <B.

5. Postulate 1-3-1: Protractor Post.
The rays of an angle can be matched up with real #s (from 1 to ___) on a protractor so that the measure of the < equals the absolute value of the ____________of the 2 #s.
55o
20o
m<A = __- __
= ___o

6. Interior or Exterior? B is ___________ C is ___________
D is ___________
in the
in the
on the B C D A

7. Post. 1-3-2: Angle Addition post.
If P is in the interior of <QRS,
then m<QRP + m<PRS = m<QRS.
If m<QRP=5xo, m<PRS=2xo, & m<QRS=84o,
find x _____________
m<QRP __________
& m<PRS. ___________ S P Q R

8. Types of Angles Acute angle – Right angle – Obtuse angle –
Straight angle –
Measures _________ 0o & 90o
Measures __________ 90o
Measures _________ 90o & 180o
Measures ____________ 180o

9. Adjacent Angles
2 angles that share a __________ vertex & side, but have ____ common interior parts. (They have the same vertex, but don’t overlap) such as <1 & <2.) 2 1

10. Example 1: Name an acute angle Name an obtuse angle Name a right angle
Name a straight angle S T 3 1 2 A B C

11. Assignment