Question: trigonometry problem

Mapletrighelp.mw

Hi all,

I am calculating the following :

Fa:=(Fa1*cos(wt))*cos(theta)

Fb:=(Fa1*cos(wt-120))*cos(theta-120)

Fc:=(Fa1*cos(wt-240))*cos(theta-240)

Ftotal:=Fa+Fb+Fc

Ftotal:= Fa1*1/2(3*cos(wt-theta)+cos(wt+theta)+cos(wt+theta-240)+cos(wt+theta-480))

Problem:

The exact solution I am looking for is: Ftotal:=3/2*Fa1*cos(wt-theta),     because the last three terms sum to zero i.e

(cos(wt+theta)+cos(wt+theta-240)+cos(wt+theta-480))=0,   The last three terms if we consider as phasors will add to 0.   

But Maple do not exclude these terms,  is there any command or directory which I have to use to get the exact required answer with the last three terms excluded.

Looking forward to your kind replies.

I have also included the Maple file just in case.

Kind Regards

A.Q