# Find the radius of convergence

I am trying to find the radius of convergence for the following function

$$f(x)=\sin(\pi x/4)$$

I already found the Maclaurin series of the function and applied the ratio test but seems I cant get the radius of convergence right. I find the radius

$R = 4/\pi$

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If you want somebody to find the mistake, you need to show the work that might contain the mistake. Often it is hard to guess just from the result. –  Ross Millikan Apr 23 '12 at 2:48
Perhaps you forgot the $1/n!$ factor in the coefficients of the Maclaurin series? –  anon Apr 23 '12 at 2:51
excuse me if I am stupid, do you mean $f(x)$ as a complex function? a real function $\sin[x]$ always converges.. –  Kerry Apr 23 '12 at 2:56

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