Practice Questions
The angle between two vectors \(a=\hat i-\hat k\) and \(b=\hat i-\hat j+\hat k\) is: 1. \(\cos^{-1}\frac13\) 2. \(\cos^{-1}\frac{-1}3\) 3. \(\sin^{-1}\frac{-1}3\) 4. \(90^\circ\)