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Vectors DOT Product :(

A photo of iRamie iRamie
Expand and simplify (3a+4b) *dot* (5a+6b)

a & b are both vectors

i know that the equation is
u dot v = |u|*|v|cosO
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A photo of phylloconcrete phylloconcrete
That's just simple binomial expansion
(3a+4b)x(5a+6b)
=15a^2+18ab+20ab+24b^2
=15a^2+38ab+24b^2
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A photo of k4show k4show

@phylloconcrete wrote
That's just simple binomial expansion
(3a+4b)x(5a+6b)
=15a^2+18ab+20ab+24b^2
=15a^2+38ab+24b^2



You beat me to it, we just had a test and I can confirm this is correct.
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A photo of iRamie iRamie

@k4show wrote

@phylloconcrete wrote
That's just simple binomial expansion
(3a+4b)x(5a+6b)
=15a^2+18ab+20ab+24b^2
=15a^2+38ab+24b^2



You beat me to it, we just had a test and I can confirm this is correct.



wow -__-
I feel like a dumbass :bom:
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A photo of g93 g93

@phylloconcrete wrote
That's just simple binomial expansion
(3a+4b)x(5a+6b)
=15a^2+18ab+20ab+24b^2
=15a^2+38ab+24b^2


=15|a|^2+38a(dot)b+24|b|^2

If you have the magnitude of a and b and have theta you can solve for |a(dot)b| or if you have the components of a and b you can solve for theta.
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