alexandre@emc.ufsc.br writes:
> How can I automatic reduce:
> cos(a+b+c)+cos(a+b-c) to 2*cos(a)cos(b), in a general way!!!
I don't think it simplifies to that:
(C1) cos(a+b+c)+cos(a+b-c);
(D1) COS(c + b + a) + COS(c - b - a)
(C2) trigexpand(d1);
(D2) 2 COS(a) COS(b) COS(c) - 2 SIN(a) SIN(b) COS(c)
Seems like factorization is in order
(C3) factor(d2);
(D3) - 2 (SIN(a) SIN(b) - COS(a) COS(b)) COS(c)
and a trigreduce should combine the stuff in the parens
(C4) trigreduce(d3);
(D4) 2 COS(b + a) COS(c)
maybe this is what you wanted?
Osman