Trigonometric functions of the unit cirlce

1. Dec 12, 2006

AznBoi

I just came across a problem that wants you to solve for csc of an angle in radians... However, I'm confused about the answer given.

Here is the problem:

Find the csc when t=-2pi/3, which is equivalent to -120 degrees right?

I got -2sqrt.(3)/3 but the answer in the back is -2sqrt.(3)/2 Why is it a 2 instead of a three??

The sin is -sqrt.(3)/2 and it is correct, so shouldn't the csc be the reciprocal of sin?? 1/sin theta?? so 1/(-2sqrt.(3)/3)????????

Thanks!

2. Dec 12, 2006

cristo

Staff Emeritus
Your book is wrong. $$cosec(\frac{-2\pi}{3}) = \frac{-2\sqrt{3}}{3}$$

3. Dec 12, 2006

AznBoi

wow... I think I've actually seen quite a few with 2's as the denominator. I'm pretty sure that I was right and the book was wrong. I'm astonished though, this book sucks! =/

Thanks for helping me check btw!! =]