Does any body know a expansion of : $\cos^k(\theta)$ in function of $\cos$ and/or $\sin$ but without power? For example : $\cos^2(\theta)=\frac{1}{2}(\cos(2\theta)+1)$, but i would want a generalization to the power $k$. I searched in Abramowitz and Stegun but didn't find anything !
expansion of $\cos^k(\theta)$
4
$\begingroup$
functions
recurrence-relations
-
0Just write $\cos \theta = \frac12 (e^{i\theta} + e^{-i\theta})$ and expand using the binomial theorem... – 2012-03-06
-
0Surely there is a better word for this than "development". – 2012-03-06
-
0which word should I use? – 2012-03-06
-
0"Expansion" is better. – 2012-03-07