Transcript Slide 1

Suppose S is between R and T. Use the Segment
Addition Postulate or sum of the parts = whole or
the add two parts of a line together thing to solve
for the variable.
Find the value of the variable and PB, if P is between A
and B.
Learners will be able to measure and classify angles,
congruent angles, and angle bisectors.
A ray is a part of a line. It has one endpoint and
extends indefinitely in one direction.
Rays are named stating the endpoint first and
then any other point on the ray.
If you choose a point on a line, you make exactly
two rays called opposite rays.
Name the 2 Rays…
An angle is the intersection of two noncollinear
rays at a common endpoint.
The common endpoint is called the vertex, and the
rays are the sides of the angle.
An angle can be named by a single
letter… ex: B
A
B
C
Or by three letters: a point on one
side, the vertex, and a point on the
other side.… ex: ABC
Name all angles that have B as a vertex.
Answer: 5, 6, 7, and ABG
Name the sides of 5.
Answer:
and
or
are the sides of 5.
Write another name for 6.
Answer: EBD, FBD, DBF, and DBE
are other names for 6.
a. Name all angles that have X as a vertex.
Answer:
1, 2, 3, and RXB
or RXN
b. Name the sides of 3.
Answer:
c. Write another name for 3.
Answer: AXB, AXN, NXA, BXA
There is an interior and an exterior
of an angle
A
Z
B
W
Where is point Z? W? C?
C
Angles are measured in degrees.
What are degrees?
Da sun
1 of a circle
360
A right angle is an angle with a
measurement of 90
Logically where is a 45 angle?
There are two other types of angles
beside right angles….
90 < mABC < 180
A
C
B
Obtuse: which have a measurement
greater than 90
There are two other types of angles
beside right angles….
A
mABC < 90
C
B
Acute: which have a measurement
lesser than 90
Measure TYV and classify it as
right, acute, or obtuse.
TYV is marked with
a right angle symbol,
so measuring is not necessary.
Answer:
is a right angle.
Measure WYT and classify it as
right, acute, or obtuse.
Use a protractor to find that
.
Answer:
>
is an obtuse angle.
Measure each angle named and classify
it as right, acute, or obtuse.
a. CZD
b. CZE
Answer: 150, obtuse
c. DZX
Answer: 90, right
Answer: 30, acute
Just like with congruent sides we
also have congruent angles
A
C
B
A ray or line that divides an angle
into two congruent angles is called
an angle bisector
A
C
B
A ray or line that divides an angle
into two congruent angles is called
an angle bisector
A
C
B
INTERIOR DESIGN Wall stickers of standard shapes
are often used to provide a stimulating environment
for a young child’s room. A five-pointed star sticker
is shown with vertices labeled. Find mGBH and
mHCI if
GBH
HCI, mGBH
2x + 5, and
mHCI
3x – 10.
Given
Definition of congruent angles
Substitution
Add 10 to each side.
Subtract 2x from each side.
Use the value of x to find the measure of one angle.
Given
or 35
Simplify.
Since
Answer: Both
.
measure 35.
SIGNS A railroad crossing sign forms congruent
angles. In the figure, WVX
ZVY. If mWVX
and mZVY
10a – 20, find the actual measurements of
WVX and ZVY.
Answer:
7a + 13
Homework:
Lesson 1-4, p. 33
# 4-36 even
42, 50