Can anyone explain why (cos(x))^2 = (1+cos(2x))/2 ?
Mar 7, 2007 #2 ziad1985 236 0 cos(x)=(Exp(ix)+Exp(-ix))/2 right? do u know this formula? square before and after the '=' then simplify it..
cos(x)=(Exp(ix)+Exp(-ix))/2 right? do u know this formula? square before and after the '=' then simplify it..
Mar 7, 2007 #3 HallsofIvy Science Advisor Homework Helper 41,833 963 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?
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?