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+--- Thread: Trig functions in CAS (/thread-2919.html)
Trig functions in CAS - phgerin - 01-24-2015 05:47 PM
Working with some trigonometric expressions, I want to rewrite sin(6x) to sin(3x+3x)=2*cos(3x)*sin(3x)
How can I do that with the Prime ?
RE: Trig functions in CAS - Eddie W. Shore - 01-27-2015 01:16 PM
You probably just have to play around the CAS commands. I don't think there is a built in function that breaks down sin(6x) to sin(3x + 3x).
The trigexpand command will expand such expressions as cos(nx) and sin(nx) into a polynomial. Using tcollect I was able to go the other way:
tcollect(2*sin(3x)*cos(3x)) -> sin(6x)
trigexpand(sin(6x)) -> (32*cos^5 x - 32*cos^3 + 6*cos x)*sin x