Find the angle between two vectors with the help of scalar product .

Explanation

If the `theta ` is the angle between `vec(A) and vec(B) ` , then vector product ,
`vec(A). vec(B) = AB cos theta `
` :. cos theta = (vec(A).vec(B))/(|vec(A)||vec(B)|)`
` :. cos theta = (vec(A).vec(B))/(AB)`
` :. theta = cos^(-1)((vec(A).vec(B))/(AB))`
In Cartesian co-ordinate system ,
`cos theta = ((A_(x)B_(x)+A_(y)B_(y)+A_(z)B_(z)))/((sqrtA_(x)^(2)+A_(y)^(2)+A_(z)^(2))(sqrt(B_(x)^(2)+B_(y)^(2)+B_(z)^(2))))`