Complex Numbers: 265.6/_0 - j1.68 * 120/_-18.2

[kris_perry2k]

Hi, i have a problem how do i solve this:

265.6/_0 - j1.68 * 120/_-18.2

where /_ is the phase angle.

The answer has been given as 279/_-43 , but i dont know how to work it out. Can anyone explain.

 

[steve_b]

Hi, i have a problem how do i solve this:

265.6/_0 - j1.68 * 120/_-18.2

where /_ is the phase angle.

The answer has been given as 279/_-43 , but i dont know how to work it out. Can anyone explain.

===================

I'm going to work in rectangular coordinates since it's easier to type. And I'm going to round off as I go.

The multiplication part has to be done first, so let's convert
the 120/_-18.2 to rectangular coordinates:

120 cos(-18.2) = 114

120 sin(-18.2) = -37.5j

Multiply this by -1.68j :

-1.68j(114 - 37.5j) = -62.5 - 191.5j

Since 265.5 /_0 is purely real we add to get:

265.5 - 62.5 - 191.5j = 203 - 191.5j

Converting this to polar form:

mag = sqrt(203^2 + (-191.5)^2) = 279.1

angle = arctan (-191.5/203) = -43.3 degrees

Hope that helps...

Steve

 

[kris_perry2k]

thanks for ur help, thats exactly what im looking for!!