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Mathematics 19 Online
OpenStudy (anonymous):

Need help dividing complex number into polar form

OpenStudy (anonymous):

OpenStudy (anonymous):

I got up to 5cis(2pi/3-pi/4) but idk how 2pi-pi = 5pi?

OpenStudy (anonymous):

v^-1 and then you can add the angles v^-1 = (1/2M)cis(-pi/4)

OpenStudy (anonymous):

w/v = w*(v^-1)

OpenStudy (anonymous):

Sorry, I don't understand?

OpenStudy (anonymous):

\[v^{-1}=\frac{ 1 }{ 2M }cis \left( -\frac{ \pi }{ 4 } \right)\] \[\frac{ w }{ v }=w\cdot v^{-1}=10M cis \left( \frac{ 2\pi }{ 3 } \right)\cdot \frac{ 1 }{ 2M }cis \left( -\frac{ \pi }{ 4 } \right)\]

OpenStudy (anonymous):

Yeah, and I got 5cis (2pi/3 - pi/4)

OpenStudy (anonymous):

and the answer is 5cis(5pi/4) but I don't understand how to get the 5pi?

OpenStudy (usukidoll):

cis? you mean cos right

OpenStudy (anonymous):

\[5cis \left( \frac{ 2\pi }{ 3 }-\frac{ \pi }{ 4 } \right)=5 cis \left( \frac{ 8\pi }{ 12 }-\frac{ 3\pi }{ 12 } \right)\]

OpenStudy (anonymous):

@UsukiDoll The question says cis

OpenStudy (usukidoll):

what?

OpenStudy (usukidoll):

oh wow gotta be a typo

OpenStudy (anonymous):

cos + i sin

OpenStudy (anonymous):

cis = cos + i sin

OpenStudy (usukidoll):

ha ha very funny

OpenStudy (usukidoll):

cuz I sign x)

OpenStudy (anonymous):

@pgpilot326 why is 2pi and pi equal to 8pi and 3pi?

OpenStudy (anonymous):

\[w=10M cis \left( \frac{ 2 \pi }{ 3 } \right)=10m \left( \cos \left( \frac{ 2 \pi }{ 3 } \right)+i \sin \left( \frac{ 2 \pi }{ 3 } \right) \right)\]

OpenStudy (anonymous):

\[v^{-1}=\frac{ 1 }{ 2m }cis\left( -\frac{ \pi }{ 4 } \right)= \frac{ 1 }{ 2m }\left( \cos\left( -\frac{ \pi }{ 4 } \right)+i \sin\left( -\frac{ \pi }{ 4 } \right) \right)\]

OpenStudy (anonymous):

when you multiply complex numbers in polar form, you multiply the magnitudes of the vectors and add the angles. in order to add fractions you need a common denominator. do you follow?

OpenStudy (anonymous):

Yeah I think

OpenStudy (anonymous):

Thanks

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