Two Different Angle Vector Formulas ?

Oct 2012
1,314
21
USA
Formula to find the angle between vectors:

\(\displaystyle |a|\,\,|b| = \cos\theta\)

or

\(\displaystyle \cos\theta = \dfrac{a\,\,*\,\,b}{|a|\,\,|b|}\)

where a and b are vectors

When should we use one formula rather than the other?
 

Plato

MHF Helper
Aug 2006
22,507
8,664
Formula to find the angle between vectors:

\(\displaystyle {a\cdot b} ={|a|\,\,|b|} \cos\theta\)

or

\(\displaystyle \cos\theta = \dfrac{a\,\,*\,\,b}{|a|\,\,|b|}\)

where a and b are vectors

When should we use one formula rather than the other?
Well if you know middleschool basic algebra, then you realize they are identical.
 
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