1. An Inverse Function What was that again?
6-5 Inverse Trig
An Inverse Function
What was that again?

2. Get out those Calculators
Please find the following:
sin cos-10
sin cos-1.5
sin cos-11
sin-1(-.5) cos-1(-.5)
sin-1(-1) cos-1(-1)

3. What is an inverse function?
What is the notation?
Arc = “-1”
In a way, you have been practicing the inverse trig process. In section 7-6, you had the trig value and found the angle.

4. f(x) = sin x its inverse would be
What is the problem here?
The inverse ISN’T a function!!

5. How do we take care of that?
Lets look at the graphs:
Therefore, there are limits on the answers that you can get.
Use your calculator to find cos-1(-.5)
What did you see?

6. Each function has a limited Range
For sin-1x, csc-1x, tan-1x
QI or QIV (go clockwise!)
For cos-1x, sec-1x, cot-1x
QI or QII

7. REMEMBER
With inverse trig you give only ONE answer!! The answer must be the closest answer to 0.
An answer in quadrant 4 such as 300 must be given as -60. BE Careful!!

8. A Hint
To give yourself something to remember, use the phrase “What angle has a” for the symbol -1. SO, lets try some problems.