Solving for the Real part of a complex number












0












$begingroup$


I have the following two complex values:



$A = a e^{j omega t + theta }$



$B = b e^{j omega t + theta}$



where $j = sqrt{-1}$.



I am trying to find the real part of the product AB.



So far I've done this: $A B = a b e^{2 j omega t+ theta}$



I am not sure where to go from here with the complex variables...










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$endgroup$












  • $begingroup$
    Please use MathJax to format your question
    $endgroup$
    – saulspatz
    Jan 20 at 0:44










  • $begingroup$
    The exponent should be $2jomega t + 2theta$
    $endgroup$
    – Ross Millikan
    Jan 20 at 2:48
















0












$begingroup$


I have the following two complex values:



$A = a e^{j omega t + theta }$



$B = b e^{j omega t + theta}$



where $j = sqrt{-1}$.



I am trying to find the real part of the product AB.



So far I've done this: $A B = a b e^{2 j omega t+ theta}$



I am not sure where to go from here with the complex variables...










share|cite|improve this question











$endgroup$












  • $begingroup$
    Please use MathJax to format your question
    $endgroup$
    – saulspatz
    Jan 20 at 0:44










  • $begingroup$
    The exponent should be $2jomega t + 2theta$
    $endgroup$
    – Ross Millikan
    Jan 20 at 2:48














0












0








0





$begingroup$


I have the following two complex values:



$A = a e^{j omega t + theta }$



$B = b e^{j omega t + theta}$



where $j = sqrt{-1}$.



I am trying to find the real part of the product AB.



So far I've done this: $A B = a b e^{2 j omega t+ theta}$



I am not sure where to go from here with the complex variables...










share|cite|improve this question











$endgroup$




I have the following two complex values:



$A = a e^{j omega t + theta }$



$B = b e^{j omega t + theta}$



where $j = sqrt{-1}$.



I am trying to find the real part of the product AB.



So far I've done this: $A B = a b e^{2 j omega t+ theta}$



I am not sure where to go from here with the complex variables...







complex-analysis






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 20 at 2:45









David G. Stork

11k41432




11k41432










asked Jan 20 at 0:41









articatarticat

63




63












  • $begingroup$
    Please use MathJax to format your question
    $endgroup$
    – saulspatz
    Jan 20 at 0:44










  • $begingroup$
    The exponent should be $2jomega t + 2theta$
    $endgroup$
    – Ross Millikan
    Jan 20 at 2:48


















  • $begingroup$
    Please use MathJax to format your question
    $endgroup$
    – saulspatz
    Jan 20 at 0:44










  • $begingroup$
    The exponent should be $2jomega t + 2theta$
    $endgroup$
    – Ross Millikan
    Jan 20 at 2:48
















$begingroup$
Please use MathJax to format your question
$endgroup$
– saulspatz
Jan 20 at 0:44




$begingroup$
Please use MathJax to format your question
$endgroup$
– saulspatz
Jan 20 at 0:44












$begingroup$
The exponent should be $2jomega t + 2theta$
$endgroup$
– Ross Millikan
Jan 20 at 2:48




$begingroup$
The exponent should be $2jomega t + 2theta$
$endgroup$
– Ross Millikan
Jan 20 at 2:48










1 Answer
1






active

oldest

votes


















1












$begingroup$

$$A B = a b e^{2 (j omega t + theta)} = underbrace{a b [ cos (2 (j omega t + theta))}_{real} + i sin (2 (j omega t + theta))]$$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    I forgot to mention that for engineering notation, j = sqrt(-1)
    $endgroup$
    – articat
    Jan 20 at 1:31










  • $begingroup$
    A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
    $endgroup$
    – David G. Stork
    Jan 20 at 2:45










  • $begingroup$
    Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
    $endgroup$
    – articat
    Jan 20 at 17:00










  • $begingroup$
    @articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
    $endgroup$
    – David G. Stork
    Jan 20 at 19:59













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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

$$A B = a b e^{2 (j omega t + theta)} = underbrace{a b [ cos (2 (j omega t + theta))}_{real} + i sin (2 (j omega t + theta))]$$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    I forgot to mention that for engineering notation, j = sqrt(-1)
    $endgroup$
    – articat
    Jan 20 at 1:31










  • $begingroup$
    A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
    $endgroup$
    – David G. Stork
    Jan 20 at 2:45










  • $begingroup$
    Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
    $endgroup$
    – articat
    Jan 20 at 17:00










  • $begingroup$
    @articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
    $endgroup$
    – David G. Stork
    Jan 20 at 19:59


















1












$begingroup$

$$A B = a b e^{2 (j omega t + theta)} = underbrace{a b [ cos (2 (j omega t + theta))}_{real} + i sin (2 (j omega t + theta))]$$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    I forgot to mention that for engineering notation, j = sqrt(-1)
    $endgroup$
    – articat
    Jan 20 at 1:31










  • $begingroup$
    A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
    $endgroup$
    – David G. Stork
    Jan 20 at 2:45










  • $begingroup$
    Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
    $endgroup$
    – articat
    Jan 20 at 17:00










  • $begingroup$
    @articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
    $endgroup$
    – David G. Stork
    Jan 20 at 19:59
















1












1








1





$begingroup$

$$A B = a b e^{2 (j omega t + theta)} = underbrace{a b [ cos (2 (j omega t + theta))}_{real} + i sin (2 (j omega t + theta))]$$






share|cite|improve this answer









$endgroup$



$$A B = a b e^{2 (j omega t + theta)} = underbrace{a b [ cos (2 (j omega t + theta))}_{real} + i sin (2 (j omega t + theta))]$$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Jan 20 at 0:47









David G. StorkDavid G. Stork

11k41432




11k41432












  • $begingroup$
    I forgot to mention that for engineering notation, j = sqrt(-1)
    $endgroup$
    – articat
    Jan 20 at 1:31










  • $begingroup$
    A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
    $endgroup$
    – David G. Stork
    Jan 20 at 2:45










  • $begingroup$
    Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
    $endgroup$
    – articat
    Jan 20 at 17:00










  • $begingroup$
    @articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
    $endgroup$
    – David G. Stork
    Jan 20 at 19:59




















  • $begingroup$
    I forgot to mention that for engineering notation, j = sqrt(-1)
    $endgroup$
    – articat
    Jan 20 at 1:31










  • $begingroup$
    A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
    $endgroup$
    – David G. Stork
    Jan 20 at 2:45










  • $begingroup$
    Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
    $endgroup$
    – articat
    Jan 20 at 17:00










  • $begingroup$
    @articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
    $endgroup$
    – David G. Stork
    Jan 20 at 19:59


















$begingroup$
I forgot to mention that for engineering notation, j = sqrt(-1)
$endgroup$
– articat
Jan 20 at 1:31




$begingroup$
I forgot to mention that for engineering notation, j = sqrt(-1)
$endgroup$
– articat
Jan 20 at 1:31












$begingroup$
A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
$endgroup$
– David G. Stork
Jan 20 at 2:45




$begingroup$
A recommendation: Always update your problem with such information (rather than make a comment), so that helpers will better see it. (See my edit to your problem.)
$endgroup$
– David G. Stork
Jan 20 at 2:45












$begingroup$
Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
$endgroup$
– articat
Jan 20 at 17:00




$begingroup$
Thank you for the recommendation. In regards to the solution, it is still imaginary because j is in the real part right? Would I then have to take the magnitude of the solution?
$endgroup$
– articat
Jan 20 at 17:00












$begingroup$
@articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
$endgroup$
– David G. Stork
Jan 20 at 19:59






$begingroup$
@articat: No. A complex number $z$ is made of a real part and an imaginary part. $z = {rm real~part} + {rm imaginary~part} = underbrace{a}_{real} + underbrace{i b}_{imaginary}$. You are thinking of the magnitude.
$endgroup$
– David G. Stork
Jan 20 at 19:59




















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