The magnitude of a vector `u` is the square root of its dot product by itself, because
`u*u=||u||*||u||*cos(theta),`
and `theta=0,` `cos(theta)=1.`
I suppose that `i` and `j` are orthonormal. Therefore
`||u||=sqrt(u*u)=sqrt((12i-16j)*(12i-16j))=`
`=sqrt(12*12+(-16)*(-16))=4sqrt(3*3+4*4)=4sqrt(25)=20.`
This is the answer.
The magnitude of a vector `u` is the square root of its dot product by itself, because
`u*u=||u||*||u||*cos(theta),`
and `theta=0,` `cos(theta)=1.`
I suppose that `i` and `j` are orthonormal. Therefore
`||u||=sqrt(u*u)=sqrt((12i-16j)*(12i-16j))=`
`=sqrt(12*12+(-16)*(-16))=4sqrt(3*3+4*4)=4sqrt(25)=20.`
This is the answer.
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