Is there a way of reducing $4sin(a)sin(b)-sin(a+c)sin(b)-sin(a)sin(b+d)$ using the gonionmetric identities?











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I'm currently working on a problem and stumbled on this equation that I'm unable to reduce using the standard goniometric identities. Perhaps the formula is impossible to reduce but any help is appreciated.



The formula I'm trying to reduce:




$$Av^{h}_{i}=4sin(a)sin(b)-sin(a+c)sin(b)-sin(a)sin(b+d)$$



[added from a comment: I've got $a=pi ki$, $b=pi kl$, $c=pi k$, and $d=pi l$, where $i$, $j$, $k$, $l$ are positive integers.]




I've tried to use the identity:



$$sin(a+b)+sin(a-b)=2sin(a)cos(b)$$



But this doesn't get me any further than a massive mess of equations. Again, perhaps the equation cannot be reduced further, but my teacher pointed out that it is indeed possible, it just takes alot of writing.



Any help is appreciated.










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  • Wolfram Alpha also come up with nothing really useful. Do you have any additional information, such as relationships among $a, b, c, d$? For example (as a wild guess), are they the four angles of a quadrilateral?
    – David K
    Nov 15 at 15:20










  • @DavidK I might have something for them but probably nothing useful either. I've got: $a=pi k i$, $b=pi k l$, $c=pi k$ and $d=pi l$, where $i,j,k,l$ are positive integers.
    – S. Crim
    Nov 15 at 19:23






  • 2




    $sin(npi) = 0$ for any integer $n.$ That would simplify your formula rather dramatically!
    – David K
    Nov 15 at 21:45















up vote
1
down vote

favorite












I'm currently working on a problem and stumbled on this equation that I'm unable to reduce using the standard goniometric identities. Perhaps the formula is impossible to reduce but any help is appreciated.



The formula I'm trying to reduce:




$$Av^{h}_{i}=4sin(a)sin(b)-sin(a+c)sin(b)-sin(a)sin(b+d)$$



[added from a comment: I've got $a=pi ki$, $b=pi kl$, $c=pi k$, and $d=pi l$, where $i$, $j$, $k$, $l$ are positive integers.]




I've tried to use the identity:



$$sin(a+b)+sin(a-b)=2sin(a)cos(b)$$



But this doesn't get me any further than a massive mess of equations. Again, perhaps the equation cannot be reduced further, but my teacher pointed out that it is indeed possible, it just takes alot of writing.



Any help is appreciated.










share|cite|improve this question
























  • Wolfram Alpha also come up with nothing really useful. Do you have any additional information, such as relationships among $a, b, c, d$? For example (as a wild guess), are they the four angles of a quadrilateral?
    – David K
    Nov 15 at 15:20










  • @DavidK I might have something for them but probably nothing useful either. I've got: $a=pi k i$, $b=pi k l$, $c=pi k$ and $d=pi l$, where $i,j,k,l$ are positive integers.
    – S. Crim
    Nov 15 at 19:23






  • 2




    $sin(npi) = 0$ for any integer $n.$ That would simplify your formula rather dramatically!
    – David K
    Nov 15 at 21:45













up vote
1
down vote

favorite









up vote
1
down vote

favorite











I'm currently working on a problem and stumbled on this equation that I'm unable to reduce using the standard goniometric identities. Perhaps the formula is impossible to reduce but any help is appreciated.



The formula I'm trying to reduce:




$$Av^{h}_{i}=4sin(a)sin(b)-sin(a+c)sin(b)-sin(a)sin(b+d)$$



[added from a comment: I've got $a=pi ki$, $b=pi kl$, $c=pi k$, and $d=pi l$, where $i$, $j$, $k$, $l$ are positive integers.]




I've tried to use the identity:



$$sin(a+b)+sin(a-b)=2sin(a)cos(b)$$



But this doesn't get me any further than a massive mess of equations. Again, perhaps the equation cannot be reduced further, but my teacher pointed out that it is indeed possible, it just takes alot of writing.



Any help is appreciated.










share|cite|improve this question















I'm currently working on a problem and stumbled on this equation that I'm unable to reduce using the standard goniometric identities. Perhaps the formula is impossible to reduce but any help is appreciated.



The formula I'm trying to reduce:




$$Av^{h}_{i}=4sin(a)sin(b)-sin(a+c)sin(b)-sin(a)sin(b+d)$$



[added from a comment: I've got $a=pi ki$, $b=pi kl$, $c=pi k$, and $d=pi l$, where $i$, $j$, $k$, $l$ are positive integers.]




I've tried to use the identity:



$$sin(a+b)+sin(a-b)=2sin(a)cos(b)$$



But this doesn't get me any further than a massive mess of equations. Again, perhaps the equation cannot be reduced further, but my teacher pointed out that it is indeed possible, it just takes alot of writing.



Any help is appreciated.







trigonometry






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share|cite|improve this question













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edited Nov 16 at 11:21









Blue

47k870148




47k870148










asked Nov 15 at 13:25









S. Crim

10110




10110












  • Wolfram Alpha also come up with nothing really useful. Do you have any additional information, such as relationships among $a, b, c, d$? For example (as a wild guess), are they the four angles of a quadrilateral?
    – David K
    Nov 15 at 15:20










  • @DavidK I might have something for them but probably nothing useful either. I've got: $a=pi k i$, $b=pi k l$, $c=pi k$ and $d=pi l$, where $i,j,k,l$ are positive integers.
    – S. Crim
    Nov 15 at 19:23






  • 2




    $sin(npi) = 0$ for any integer $n.$ That would simplify your formula rather dramatically!
    – David K
    Nov 15 at 21:45


















  • Wolfram Alpha also come up with nothing really useful. Do you have any additional information, such as relationships among $a, b, c, d$? For example (as a wild guess), are they the four angles of a quadrilateral?
    – David K
    Nov 15 at 15:20










  • @DavidK I might have something for them but probably nothing useful either. I've got: $a=pi k i$, $b=pi k l$, $c=pi k$ and $d=pi l$, where $i,j,k,l$ are positive integers.
    – S. Crim
    Nov 15 at 19:23






  • 2




    $sin(npi) = 0$ for any integer $n.$ That would simplify your formula rather dramatically!
    – David K
    Nov 15 at 21:45
















Wolfram Alpha also come up with nothing really useful. Do you have any additional information, such as relationships among $a, b, c, d$? For example (as a wild guess), are they the four angles of a quadrilateral?
– David K
Nov 15 at 15:20




Wolfram Alpha also come up with nothing really useful. Do you have any additional information, such as relationships among $a, b, c, d$? For example (as a wild guess), are they the four angles of a quadrilateral?
– David K
Nov 15 at 15:20












@DavidK I might have something for them but probably nothing useful either. I've got: $a=pi k i$, $b=pi k l$, $c=pi k$ and $d=pi l$, where $i,j,k,l$ are positive integers.
– S. Crim
Nov 15 at 19:23




@DavidK I might have something for them but probably nothing useful either. I've got: $a=pi k i$, $b=pi k l$, $c=pi k$ and $d=pi l$, where $i,j,k,l$ are positive integers.
– S. Crim
Nov 15 at 19:23




2




2




$sin(npi) = 0$ for any integer $n.$ That would simplify your formula rather dramatically!
– David K
Nov 15 at 21:45




$sin(npi) = 0$ for any integer $n.$ That would simplify your formula rather dramatically!
– David K
Nov 15 at 21:45















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