Re: cos(12 degress)*cos(24 degrees)*cos(48 degrees)*cos(96 degrees)

Brad Cooper wrote:

I thought to use MuPAD 4.0 to calculate the exact value of

cos(12 degress)*cos(24 degrees)*cos(48 degrees)*cos(96 degrees)

i.e. cos(PI/15)*cos(2*PI/15)*cos(4*PI/15)*cos(8*PI/15)

I used...

rewrite(cos(PI/15)*cos(2*PI/15)*cos(4*PI/15)*cos(8*PI/15),exp)
expand(%)
simplify(%)

and other combinations along those lines, but could not get MuPAD to do
the calculation.


You need a little trick:

do
subs(%, PI = 15*X);
expand(%);
subs(%, X = PI/15);
simplify(%);

and everything will work.


--
Stefan Wehmeier
stefanw@xxxxxxxx
.

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