Download Geometry 1-4 Angle Measure A. Definitions 1. Astronomer Claudius

Geometry 1-4 Angle Measure
A. Definitions
1. Astronomer Claudius Ptolemy divided a __________ into 360
parts, which later became known as a degree.
2. A ray is part of a _________, it has one endpoint and extends
indefinitely in one direction.
D
E
Ray DE, written DE .
3. If you choose a point on a _______________, that point
determines exactly two rays called opposite rays.
C
D
E
DC and DE are opposite rays
4. An angle is the intersection of two _______________ rays at a
common endpoint.
5. The rays are called the sides of the angle.
6. The common endpoint is called the vertex.
Side BA
Vertex B
B
2
Side BC
E
A
∠ABC
∠ _____
∠ __
∠ __
Call this:
D
C
7. Point D lies in the __________ of the angle.
8. Point E lies in the exterior of the angle.
A
G
Example 1:
a.) Using letters, name all the angles
that have point B as a vertex.
5
c.) Write another name for ∠6 . ______
6
7
D
3
______, ______, ______, ______
b.) Name the sides of ∠5 . ______, ______
B
E
F
4
B. Angles
1. A right angle is ____ .
2. An acute angle is ____________ 90 .
3. An obtuse angle is greater than 90 , but less than _____.
Example 2: Measure each angle and classify it as right, obtuse, or
acute.
a.) ∠TYV =______ __________
b.) ∠WYT =______ __________
c.) ∠TYU =______ ___________
U
V
T
W
Y
S
X
4. Angles that have the same measure are said to be congruent
angles.
Example 3: Find the value of x and ∠ABC .
x = ______
∠ABC =______
A
C
12 x + 8
B 14 x − 12
D
E
5. A ray that divides an angle into two __________ angles is called
an angle bisector.
Example 4: SV is an angle bisector of
∠RST , find x and m∠RST
R
S
x = ____
m ∠RST =_______
HW: Geometry, Sec 1-4 p. 34-36
13-39 odd, 42 - 43, 50 -66 all
6x + 2
V
9 x − 13
T