Re: How Expand?
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- Subject: [mg127845] Re: How Expand?
- From: David Bailey <dave at removedbailey.co.uk>
- Date: Sun, 26 Aug 2012 02:52:23 -0400 (EDT)
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On 24/08/2012 10:08, news wrote: > Hi folks, > > How can I expand the following : > > [ 1 + cos(x) + i sin(x) ]^3 > > to obtain; > > 8 cos(x/2)^3 [cos(3x/2)+ i sin(3x/2)] > > Thanks a lot. > > Max. > I addition to the comments of others, I would like to add, that if you simply want to check an identity, it is easier to use: In:= ( 1 + Cos[x] + I Sin[x] )^3==8 Cos[x/2]^3 (Cos[3x/2]+ I Sin[3x/2])//Simplify Out= True (I.e. simplifying the assertion that the LHS == RHS, comes back with True) This works in many situations in which it is extremely hard to force Mathematica to come up with a desired transformation spontaneously. David Bailey http://www.dbaileyconsultancy.co.uk