Question

is cos inverse (cos^-1) the same thing as secant?

Answer 1

No. Inverse trig functions return angles. secant will return a length as will all trig functions.

Answer 2

I made this sheet a while ago, i think you will find this fairly useful for trig.
http://learnix.net/ultimate-trig-cheat-sheet/

Answer 3

It's easy to confuse arccos, AKA inverse cosine with the algebraic notation of x^(-1). In the case of trig functions, it means something else...it means that it's the inverse function.

Does that make sense?

Answer 4

ok thanks! then how do you solve the problem \[\cos^{-1} (\cos (17\pi/5))\]

Answer 5

@agentc0re

Answer 6

First you would need to calculate the inner part.

Answer 7

@agentc0re ok but how do i calculate it without a calculator since it is not a unit circle value

Answer 8

wait isnt \[\cos^{-1} \cos \] just one?

Answer 9

Well, not 1 but they do kind of "cancel" each other out.

Answer 10

ok thank you so much!! so then the answer would just be -17pi/5

Answer 11

oops not the negative

Answer 12

Here's the problem though. You're going to get an answer that is outside of the unit circle. If you try to convert that angle to a degree it's going to be much larger than 360.

Answer 13

So you'll need to be able to devise a way to know where you expect it to be on the unit circle. Make sense?

Answer 14

YES THANK YOU!!!!!!!!!!!!!!!

Answer 15

Awesome! Good luck :D