# Math Help - series expansion of cotx

1. ## series expansion of cotx

hi you,

he expansion for the cosx ... okay got it

but though i can do the long division to get tanx i can't for the series expansion of cotx

maybe you know much more than me

yes?

2. Originally Posted by pepsi
hi you,

he expansion for the cosx ... okay got it

but though i can do the long division to get tanx i can't for this

maybe you know much more than me

$\cot(z)=\sum_{n=0}^{\infty}\frac{(-1)^n 2^{2n} B_{2n}}{(2n)!} z^{2n-1}$