Download Section 1.5 Day 2 Segment and Angle Bisectors

Week 2
08.25.11
Warm Up
Circle the congruent segments and congruent angles:
1)
2)
Homework
4)
5)
6)
( 1, 3 )
17)
( -4, 3 )
18)
( 1, 2 )
19)
( 4, 6.5 )
20)
( -5, .5 )
21)
( -3, 3 )
22)
( 4 , -7 )
23)
( -0.625 , 3.5 )
24)
( -3 , 1.5 )
( 5, -7 )
( 3.5, 2 )
Geometry
1.5 Day 2
Segment
Bisector
I will bisect an angle and find the
measure of an angle using algebra
A segment, line, ray, or plane that
intersects a segment at the midpoint.
Midpoint
Ex 1
•
M
A
•
•
C
B
D
Bisector
Angle
Bisector
A ray that divides an angle in half and
creates adjacent angles that are congruent
•
A
Ex 2
•
D
C
•
B
CD Bisects ∠ ACB
m∠ ACD = m ∠ DCB
Find
missing
Angles
P
•
R
S
55º
Ex 3
QR Bisects ∠ PQS
m∠PQR = m∠PQS
2
Q
m∠PQR = m∠RQS
55º = m∠RQS
55º = m∠PQS
2
(2)55º = m∠PQS
110º = m∠PQS
Find
Angle
Bisector
S
R
Ex 4
P
m∡PQR = 70º
QS bisects ∡PQR
Q
70º
= 35º
2
O
Ex 5
P
( 5x – 46 )
Using
Algebra
OQ Bisects ∠ POR
Q
•
( 2x+ 5 )
m∡POQ = m∡QOR
5x – 46 = 2x + 5
5x - 2x - 46 = 5
3x – 46 = 5
3x = 5 + 46
3x = 51
x = 17
R
Using
Algebra
x = 17
m∡POQ = 5x – 46
m∡QOR = 2x + 5
= 5( 17 ) – 46
= 2( 17 ) + 5
= 85 – 46
= 34 + 5
m∡POQ = 39º
m∡QOR = 39º
Review
DO 1:
What is an angle bisector?
What is the m∡POQ?
OQ Bisects ∠ POR
O
P
( 3x + 16 )
Q
Assignment
R
( 7x - 8 )
•
Textbook page 39, 34 – 54 all except # 43