Who Discovered the Trig Sum Formulas?

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ImAnEngineer
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sin(a + b) = sin(a)cos(b) + cos(a)sin(b)
sin(a - b) = sin(a)cos(b) - cos(a)sin(b)

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

Who first derived them? When, and how?

Thanks
 

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ImAnEngineer said:
Who first derived them? When, and how?

Not how, but Howe … Julia Ward Howe, in 1861, derived them, and they became a Civil War marching song, to the tune now known as the Battle Hymn of the Republic. :wink:
 
tiny-tim said:
Not how, but Howe … Julia Ward Howe, in 1861, derived them, and they became a Civil War marching song, to the tune now known as the Battle Hymn of the Republic. :wink:
If it's a joke... sorry but I don't get it.
 
ImAnEngineer said:
If it's a joke... sorry but I don't get it.

:rolleyes:

try singing it! :smile:
 
tiny-tim said:
:rolleyes:

try singing it! :smile:

Struggling to get a nice melody... :P

Any serious comments?
 

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