Help with graphical technique of adding 2 sinusoids

Discussion in 'Homework Help' started by p75213, Dec 20, 2011.

  1. p75213

    Thread Starter Active Member

    May 24, 2011
    I have a problem understanding how equation 9.11 (see attached) works with Fig. 9.4 (a). Can somebody please clarify?
  2. jegues

    Well-Known Member

    Sep 13, 2010
    Put both of the sinusoids into the phasor domain, add them, and pull them back to the time domain.

    Use the cosine as your reference phasor.
  3. Rio

    New Member

    Dec 23, 2010
    u can prove that mathematically by ,, let's say A=4 , B=3
    and then assume that wt = 0 and replace it in the equation (Acoswt+Bsinwt) and write down the number you have and then when wt=-1 , and then wt = 1 and when u have it ready draw it ,, and u will have a cosine function with a small shift
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Hi p75213 - It's not particularly clear where the gap in your understanding lies. Perhaps you are not sure why one is permitted to draw the cosine and sine function vectors (phasors) as an orthogonal pair - i.e. at right angles to one another ...?? Do you understand why/how it's possible to represent a time varying function as a 'static' phasor?