Trig identities?

  • Thread starter Jenkz
  • Start date
  • #1
59
0

Homework Statement


How to get from

[tex]\sqrt{2+2cosx}[/tex]
to

2cos(x/2)

The Attempt at a Solution



I'm pretty much stuck on this.
I can only see that is simplifies by taking out the common factor 2, which isnt correct.
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,223
31
Well id cos2x=2cos2x-1, then cosx=2cos2(x/2)-1
 
  • #3
59
0
Yup, thanks!
 

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