Posted by **Dennis** on Monday, April 21, 2008 at 9:59am.

Problem:

cos[arccos(-sqrt3/2)-arcsin(-1/2)]

This is what I have:

cos [(5pi/6)-(11pi/6)]

cos (-6pi/6) or -pi

giving an answer of -1

What I am wondering is should I use the (11pi/6) or should I use (-pi/6) because of the restrictions on arcsin x (-pi/2)<=x<=(pi/2)

Thank you in advance.

- Inverses -
**bobpursley**, Monday, April 21, 2008 at 11:14am
I would use the smaller angle. It should not matter on the final answer.

- Inverses -
**Dennis**, Monday, April 21, 2008 at 11:35am
Thank you very much.

The answer doesn't change, but my trig teacher wants to see all of work, and I just wasn't sure which figure to use.

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