Help with this math Transformation

  • Thread starter kasse
  • Start date
  • #1
382
1
Can anyone explain why (cos(x))^2 = (1+cos(2x))/2 ?
 

Answers and Replies

  • #2
236
0
cos(x)=(Exp(ix)+Exp(-ix))/2 right? do u know this formula?
square before and after the '='
then simplify it..
 
  • #3
HallsofIvy
Science Advisor
Homework Helper
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If you don't want to use complex numbers, remember that cos2x= cos2 x- sin2 x so that the right hand side is (1+ cos2 x- sin2x)/2. Do you see an "obvious" way to simplify 1+ cos2 x- sin2x?
 

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