w 3 m k e i+ c untunt. this week at a glance return ch. 13 quizzes 13.5a notes assignment: 13.5...
TRANSCRIPT
WELCOME TO ALG. 2A
w3 mke i+ cunt
TODAY’S AGENDA
This Week at a Glance
Return Ch. 13 Quizzes
13.5A Notes
Assignment: 13.5 Skills Practice
THIS WEEK AT A GLANCE
Monday: 13.5A Law of Cosines
Tuesday: 13.5B Law of Cosines
Wednesday: Ch. 13A Review
Thursday: Ch. 13A Test
Friday: Begin Ch. 13B ~ Unit
Circle
CH. 13A QUIZ
2) Write an equation involving sine, cosine, or tangent that can be used to find x. Then solve the equation, rounding to the nearest degree.
CH. 13A QUIZ
Solve
3) Solve ∆ABC if mA = 20, mC = 90, and b = 10. Round measures of sides to the nearest tenth and measures of angles to the nearest degree.
CH. 13A QUIZ
4) Using the Law of Sines, find the measure of angle A when c = 15, mB = 50, and b = 12.4.
A
B
C
LESSON 13.5A
I CAN . . .
· solve problems by using Law of Cosines.
VOCABULARY
Term Definition Example
Law of Cosines
In any ABC,
Use Law of Sines when given
_______, or _______.
SASSS
S
cA
C
a
B
b
a2 = b2 + c2 – 2bc cos A
b2 = a2 + c2 – 2ac cos B
c2 = a2 + b2 – 2ab cos C
EXAMPLE 1:
In ABC, find c.
Cabbac cos2222
2c 22 1210 48cos
2c 4.83
12102
1.9c
EXAMPLE 2:
In ABC, find r.
Cabbac cos2222
2c 22 1412 62cos2c 3.182
14122
5.13c
r
EXAMPLE 3:
A ranger tower at point A is directly north of a ranger tower at point B. A fire
at point C is observed from both towers. The distance from the fire to tower A is
60 miles, and the distance from the fire to tower B is 50 miles. If mACB = 62,
find the difference between the towers.
A
B
C
50
62
60
c
Cabbac cos2222
62cos605026050 222 c
2.32832 c
3.57c
TODAY’S ASSIGNMENT
13.5 Skills Practice
#1 – 6