# Math Help - Help me to solve this 'Cot' fomular

1. ## Help me to solve this 'Cot' fomular

cot3a=(cot<3>a - 3cota)/3cot<3>a-1

<> = superscript value

I need to prove above formula.

Thanks

2. First of all, please use brackets where they're needed. Also, the ^ symbol is the symbol used for superscripts. Either that, or use LaTeX.

Anyway, are you trying to solve

$\displaystyle \cot{3a} = \frac{\cot^3{a} - 3\cot{a}}{3\cot^3a} - 1$

or

$\displaystyle \cot{3a} = \frac{\cot^3{a} - 3\cot{a}}{3\cot^3a - 1}$?