Trig, What would this reduce to?

[TheRedDevil18]

Homework Statement

cos(-225)

The Attempt at a Solution

Would it become, -cos45 ?
Just want to make sure.

 

[HallsofIvy]

Are we to assume that this is 225 degrees?

If so then 225= 360- 35, NOT 45.

 

[Mentallic]

TheRedDevil18, you're correct.

225= 360- 35

That's not right, it's 225 = 360 - 135.