Angle θ between two vectors is given by, \(\theta =cos^{-1}( \frac{u \cdot v}{|u||v|} )\); where \(u \cdot v=2(3)+(-4)(-8)=6+32=38\); \(|u|= \sqrt{ 2^{2} + (-4)^{2} } = \sqrt{4+16} = \sqrt{20}\) and \(|v|=\sqrt{ 3^{2} + (-8)^{2} } = \sqrt{9+64} = \sqrt{73}\).
Therefore, \(\theta =cos^{-1}( \frac{38}{ \sqrt{20} \times \sqrt{73} } )=cos^{-1}0.9945=6.0^o\)
