
Calculus Calculus Math Forum 
 LinkBack  Thread Tools  Display Modes 
February 14th, 2017, 10:54 PM  #1 
Member Joined: Nov 2014 From: SG Posts: 55 Thanks: 1  Solve using phasors and express it in time domain
Perform the following using addition using phasors (a) V = 40sin2t + 60cos(3t45 degree) How do I solve it if the angular frequency is difference? The youtube video teaches only if the angular frequency is the same For example , this link 
February 15th, 2017, 04:39 AM  #2 
Senior Member Joined: Sep 2015 From: USA Posts: 1,780 Thanks: 919 
You can't really apply phasors to sinusoids of different frequencies. Their phase difference is time varying. are you sure that the second frequency shouldn't be $2t  45^\circ ?$ 
February 15th, 2017, 09:12 PM  #3 
Member Joined: Nov 2014 From: SG Posts: 55 Thanks: 1  
February 16th, 2017, 05:39 AM  #4 
Senior Member Joined: Sep 2015 From: USA Posts: 1,780 Thanks: 919  the method usually used is $\cos(a)\cos(b) =\dfrac 1 2 ( \cos(a+b) + \cos(ab))$ This gets you the standard 2x frequency, (a+b), which is usually filtered out, and the "beat frequency", (ab), which you're familiar with if you've ever tuned a guitar. 

Tags 
domain, express, phasors, solve, time 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Have fun & solve math problems at the same time  zeus vs. Monsters  peaksel  Math Software  3  March 4th, 2016 04:58 PM 
Express the Area, but this time it is open?  Shamieh  Algebra  3  May 20th, 2013 06:53 PM 
How do I express the domain in 'Interval Notation'?  elifast  Algebra  3  September 20th, 2012 07:21 PM 
Solve. Express in lowest terms.  grace25  Elementary Math  8  June 26th, 2012 06:04 AM 
Integration over open domain or close domain  good_phy  Calculus  1  October 12th, 2008 09:26 AM 