Download 6.4 Cofunctions

6.4 Cofunctions
Students will learn about cofunctions in trigonometry
Trigonometric Cofunctions
The sine of an angle is equal to the cosine of its complement.
A
sin∠A = _______
cos∠B = _______
Key Fact
13
5
C
B
12
Example Problems
If sin(49)=cos(x), find the value of x
that would make this statement true.
If A and B are complimentary angles,
and sinA = 3 , what is the cosB?
5
Trigonometry Cofunctions Part II
Another way of saying the same thing
Sin∠A =Cos∠B
A
We know this is true
and
∠B = 90 ­ ∠A
So this is also true
SinA = CosB
C
B
SinA = Cos(90 ­ A)
Independent Practice
In
CAT, find the sinA and cosT.
A
sinA = _____
26
12
C
10
cosT = ____
Is sinA = cosT?
T
For problems a ­ f, find the missing value of cosine.
2