1. Quiz
1) Sketch an angle of and then find its reference angle
2) Find the supplementary angle to
3) Find the arccos( ) in both radians and degrees.
4) Find the arcsin(.3279) in both radians and degrees.

2. 1) Sketch an angle of and then find its reference angle
Quiz
1) Sketch an angle of and then find its reference angle
7/3 = which means that it goes all the way around and ends up in he first quadrant y x
Since it is 180º half way around the reference angle is 180 – 125 = 55º

3. Quiz
2) Find the supplementary angle to

4. Quiz
3) Find the arccos( ) in both radians and degrees.
arccos( ) =
Because the cos(30) = and the cos( ) =
4) Find the arcsin(.3279) in both radians and degrees.
arcsin(.3279) =
Because the sin of either one = if you are in the right mode

5. Law of Sines - Radians
Nothing changes when the angles are shown in radians – you just need to make certain your calculator is in radian mode A
The law of sines is still the same b c C a B

6. Law of Sines
Find side c
Now we cross multiply – make sure the calculator is in radian mode when taking the sin A
b = 32ft c C
B = a
C = B

7. Law of Sines
Find angle B
Now we cross multiply A
b = 23ft
A = c C
a = 14ft
Now we simply do 2nd sin (.7128) to get the angle B

8. Area of Any Triangle Using Sines
We can find the area of any triangle using two of the sides and the sine of the angle that is between the two sides A
Make sure the angle is between the two sides b c C
Angle A is between b and c, Angle B is between a and c, Angle C is between a and b a B

9. Area of Any Triangle Using Sines
The formula is easy to use – just be sure that your calculator is in the proper mode A b c C a
In general its ½(two of the sides)(sin of the angle between them) B

10. Area of Any Triangle Using Sines
Find the area A
b = 23ft
C = c C
a = 14ft B

11. Area of Any Triangle Using Sines
Find the area A
b = 34ft C
c = 18ft a
A = B