Trivia: Question about arranging terms - 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: Trivia: Question about arranging terms (/thread-9533.html) Trivia: Question about arranging terms - DrD - 11-19-2017 03:39 PM If there is a lexicon formality, how should equal power terms involving cos() and sin() be displayed in "proper" order? Here's an example: y:=cos(x^4)^2; y'; ==> -2*4*x^3*sin(x^4)*cos(x^4) Notice the factoring order collect(y'); ==> -8*x^3*cos(x^4)*sin(x^4) The cos() and sin() get reversed here. (In this case increasing power order): Without any mathematical difference, what, if any, is the proper, or most formal way to express the ordering of the trig terms? RE: Trivia: Question about arranging terms - salvomic - 11-19-2017 03:58 PM (In this case increasing power order): Without any mathematical difference, what, if any, is the proper, or most formal way to express the ordering of the trig terms? [/quote] In the old Italian books of trigonometry we have: SIN, COS, TAN and decreasing power order (x^4, x^3, x^2..., about my math professor), but if (generally) COS in x and SIN is y, we should have COS, SIN, TAN, I think...