What is the taylor series in sigma notation of: sin2(x)?

1 Answer
May 19, 2015

You can start by using the trig identity of sin2x=1cos2x2

we know the Maclurin series of cosx is n=0(1)nx2n(2n)!

Keep in mind here that 0!=1, so the case of n=0 is still valid.

So we can then sub in 2x in place of x to solve for cos2x

cos2x=n=0(1)n(2x)2n(2n)!

thus we get:

sin2x=1cos2x2=1212n=0(1)n(2x)2n(2n)!