B
Equivalent Trig Co-Functions
c
a
A
What do we already know? α + θ = _____
α and θ are called _________ angles.
so (90o ­ θ) = _____
sin α = ______
cos θ = ______
Conclusion?
THE CO­FUNCTION IDENTITIES
b
C
Example 1: Find all values of 0o ≤ θ ≤ 360o ...
sin 30o = cos θ
step 1:
sketch primary picture
step 2:
determine relevant quadrant
step 3:
find complement
step 4:
draw new picture
step 5:
name angles
Example 2: Find all values of 0o ≤ θ ≤ 360o ...
sec 28o = csc θ
step 1:
sketch primary picture
step 2:
determine relevant quadrant
step 3:
find complement
step 4:
draw new picture
step 5:
name angles