sin(-Ø)-6cos(-Ø)+3tan(2Ø)

Edit: Added some tex tags

This is a question on a review I am doing, my answer doesn't match up with the answer key and I am looking for some input on what I am doing wrong.

If with in quadrant IV find:

I solved for and

Using negative angle identities and the double angle identity I end up with:

Plugging in my values gives me:

Simplified to:

The answer key gives:

Not sure where I am messing up =\ any help is much appreciated.

Re: sin(-Ø)-6cos(-Ø)+3tan(2Ø)

I believe your answer is correct:

Given in the fourth quadrant then = -1.4 radians = -80.45 degrees.

Your answer matches:

but their answer is:

**EDIT

I think I may have found where whoever came up with the answer key made mistakes: if (a) they used instead of , and also (b) instead of simplifiying the term to as you have it they made it , that would explain it.

Re: sin(-Ø)-6cos(-Ø)+3tan(2Ø)

Thanks for the quick reply ebaines! That is what I was starting to think. I always assume my side is where the problem is but I am slowly learning to not always trust the given answers.