Trig functions in CAS - Printable Version +- HP Forums ( https://www.hpmuseum.org/forum)+-- Forum: HP Calculators (and very old HP Computers) ( /forum-3.html)+--- Forum: HP Prime ( /forum-5.html)+--- 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 |