DO NOW
• Pick up a folder off the table and write your
name on the tab.
• This is the folder you will turn all quizzes
and tests into.
• It will be alphabetically placed in the top
drawer of the filing cabinet.
• Find the following to the 4 decimal places
• Make sure your calculator is in radian mode or
degree mode.
• Use correct mode or your answer will be
wrong!
Mode
• Sin 2.34R = .7185
radians
• Cos 5π/8 = -.3827
radians
• Tan 125° = -1.428
degrees
• Csc 3π/5 = 1.0515
radians
• Cot 48° = .9004
degrees
• Sec 3π/7 = 4.4940
radians
• Fill in the unit circle handout:
– Degrees
– Radians
• Approximate decimals for quadrantals
– π/2 ≈1.57 R , π ≈ 3.14, 3π/2 ≈ 4.71, 2π ≈ 6.28
• We will use this same sheet the rest of the
term. Do not lose it. You will not get a new
one.
cos  , sin   tan 
u
 3
3
1
1

3
3
3
3
0
0
3
3

1
1
3
 3
u
3
3
• Notice angles that are multiples of 45°
have a 4 in the denominator in radians
• Multiples of 30° have a 6 in the
denominator
• Multiples of 60° have a 3 in the
denominator
• Approximate decimals for quadrantals
– π/2 ≈1.57 R , π ≈ 3.14, 3π/2 ≈ 4.71, 2π ≈ 6.28
• THIS WILL BE IMPORTANT LATER!
• We will use this same sheet the rest of the
term. Do not lose it. You will not get a new
one.
2
• 2.15 R
• 5π/8 2
• 1.0 R 1
• 7π/6 3
1
• 7π/3
• 4.97 R 4
θ MUST BE IN RADIANS!!
Converting from degrees to
radians and radians to degrees
• 137° to radian measure

137
137 

180 180
• 5π/11 to degree measure
5 180 900


11

11
• 147° to radians to the 4 decimal place
147 

180
 2.5656
The diameter of a circle is 20 cm and
the measure of the central angle is 130°.
A. find length of arc
B. find area of corresponding sector
• First: write the equations
• Second: draw picture and plug values
Third: solve
• θ must be in radians to use formulas
• Must be in radians not degrees. We must

13
convert:
130 
 
130º
180 18
• Formulas?
s = rθ
• Solve:
13
s  10  
18
r
k
2
2
13
10 (  )
18
k
2
2
20 cm
• Convert 20 rpms to rad/sec
20rev 2 1min
2



1min 1rev 60 sec 3 sec
• Convert 1 revolution in 4 hours to rad/min
1rev 2
1hr




4hrs 1rev 60 min 120 min
2
• Find the angular velocity of the minute
hand of a clock in one minute. Convert to
rad/sec
1rev
2 1 min




60 min 1rev 60 sec 1800 sec
30
– p. 106 # 7-17 odd, 25-39 odd
– p. 113 # 1-9, 11-17 odd, 39-42, 47-48, and
pick one from 22-24
– p.55 # 1-7 all, 8-15 all (handout/ problems
for a different book)