# Math Help - Paralell RLC circuit, calculating phasors

1. ## Paralell RLC circuit, calculating phasors

Hi,

I have a parallel RLC circuit with two phasors i'd like to combine into one.

However im not sure how to compute the angle. These are the phasors i want to find the resultant for.

$37.94\angle 71.5$

$133.33\anle -90$

I know the formula, just not sure how to find the angle.
$\frac{1}{\frac{1}{37.94} + \frac{1}{133.33}} = 29.53$

2. Originally Posted by Jones
Hi,

I have a parallel RLC circuit with two phasors i'd like to combine into one.

However im not sure how to compute the angle. These are the phasors i want to find the resultant for.

$37.94\angle 71.5$

$133.33\anle -90$

I know the formula, just not sure how to find the angle.
$\frac{1}{\frac{1}{37.94} + \frac{1}{133.33}} = 29.53$
Dear Jones,

When using the formula for impedance you have to substitute the impedances with their directions. That is why we normally use the complex number method in evaluating AC circuits. You have only substituted the magnitude of impedances which is incorrect. I suggest you to read http://www.phy.duke.edu/~fortney/phy...rcuit_note.pdf which will give you a better idea.

In solving this problem the easiest method is to draw the two phasors in a vector diagram and find the resultant vector.