Honors Geometry
Chapter 9
Law of Sines
3/22/2014
Please select a Team.
1. Team 1
2. Team 2
3. Team 3
4. Team 4
5. Team 5
6. Team 6
7. Team 7
8. Team 8
9. Team 9
10. Team 10
Response Grid
0
1
0
0
0
0
0
0
2
3
4
5
6
7
0
8
10
0
0
9
10
Countdown
Law of Sines
The Law of Sines can be used to find missing sides and angles of
oblique (non-right) triangles.
Law of Sines:
sin A sin B sin C
= =
a
b
c
Example 1
Solve the triangle described using the Law of Sines.
=
B 71=
, c 8=
, b 16
A
8
B
16
80.786
71
28.214
16.704
C
m∠A= 180 − ( 71 + 28.214 ) = 80.786
sin 71 sin C
sin 71 sin 80.786
=
=
16
8
16
a




8sin 71 = 16sin C
a
sin
71
=
16sin
80.786
8sin 71
16sin 80.786
= sin C 
a=
16


sin
71
 8sin 71 

C  = sin −1 
 = 28.214 a = 16.704
 16 
Law of Sines:
sin A sin B sin C
= =
a
b
c
Example 2
Solve the triangle described using the Law of Sines.
C
19.571 126


=
A 40=
, B 14
=
, a 52
52


40
A
14
65.448
B
sin 40 sin14
=
52
b
b sin 40 = 52sin14
52sin14
b=
sin 40
b = 19.571
m∠A= 180 − ( 40 + 14 ) = 126
sin 40 sin126
=
52
c
c sin 40 = 52sin126
52sin126
c=
sin 40
c = 65.448
B
CHECKPOINT
Find m∠A
36
.
119
A
A.a.25
b.

c.
54
B.
d.
C
8
.
C. 90
D. 119
Response Grid

0
a.
0
0
b.
c.
0
15
d.
Countdown
B
CHECKPOINT
.
Find a
A.a.3.972
b.
B.c.5.538
d.
36
A
a
25
119
C
8
.
C. 5.752
Response Grid
D. 7.652
0
a.
0
0
b.
c.
0
15
d.
Countdown
B
CHECKPOINT
.
Find c
A.a.3.028
b.
B.c.3.254
d.
c
A
36
5.752
25
119
C
8
.
C. 7.326
Response Grid
D. 11.904
0
a.
0
0
b.
c.
0
15
d.
Countdown
Team Scores
150
150
150
100
75
66.67
50
50
20
0
Team 3
Team 4
Team 2
Team 7
Team 1
Team 8
Team 9
Team 6
Team 5
Team 10
• End
Honors Geometry
Chapter 9
Law of Sines
3/22/2014
Law of Sines
The Law of Sines can be used to find missing sides and angles of
oblique (non-right) triangles.
Law of Sines:
sin A sin B sin C
= =
a
b
c
Example 1
Solve the triangle described using the Law of Sines.
=
B 71=
, c 8=
, b 16
A
8
B
16
71
C
Law of Sines:
sin A sin B sin C
= =
a
b
c
Example 2
Solve the triangle described using the Law of Sines.
C
40
A


=
A 40=
, B 14
=
, a 52
52
14
B