If the position vector ` vec a` of a point `(12 ,n)` is such that `| vec a|=13 ,` find the value of `ndot`

Explanation

Given,

the position vector of point `(12,n)`
is `12hati+nhatj`

So, `a=12hati+nhatj`

​thus,

`=∣a∣=sqrt((12)^2+n^2)
`​

`=13=sqrt((12)^2+n^2)`

`​=169=144+n^2`

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