MATLAB: Trigonometric Power Reduction Formulas using Symbolic Matlab

power reductionSymbolic Math Toolboxtrigonometric

Hi,
How can i get 1/2(1-cos(2*a)) by rewriting sin(a)^2 using Symbolic Matlab toolbox?
On the other hand if I use rewrite(.5*(1- cos(2*a)),'sin'), i will get sin(a)^2, can't I do the reverse of this process?
Thanks

Best Answer

Here, you want to change the input from "sin" from "a" to cos with "2*a". Essentially, you want make the argument of the function more complicated. The "combine" command does that.
>> syms a
>> f = sin(a)^2;
>> combine(f,'sincos')
ans =
1/2 - cos(2*a)/2
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